How to Remove and Replace Rusted on O2 Sensor

Disclaimer of Liability
This channel produces videos for entertainment purposes only. Game of Life shall not be held liable for any improper or incorrect use of the information contained within the channel’s videos. Always seek advice from a trained professional before attempting anything seen in the videos.

[@gameoflife7235]

I just did the 2nd O2 sensor, on the passenger side. There wasn't even enough clearance to get a closed end wrench over the top after cutting wires. I tried a cheap Harbor Freight air chisel to try and cut everything but the hex shape off to get some room but dulled the chisel. However with all of the impacts from the chisel it broke itself loose and turned by hand. Maybe it was just luck but might help "pretreating" it with some whacks!

[@nmartin5551]

Thanks for the vid. I always check comments on stuff like this, as it generally also produces a wealth of things I wouldn’t think of trying, in addition to the vid info. Great job!

[@Dhi-fe5eu]

Great video. I like to see how people adapt when things do not go so smoothly like when I’m working on the car.

[@bosshawg1789]

You only need a split socket for installing the new sensor. To remove the old one cut the wires and use a 22mm box end wrench or regular socket and breaker bar.

[@kevinmarshall1072]

The washers on O2 sensors are designed to provide a gas tight seal, penetrating oil can't reach the threads no matter how much you spray or how long its left. it may help if its still tight after a half turn loose but not before.

[@shaunmoeller3288]

Another good til is to put a hose clamp around the o2 sensor socket to prevent it from opening and slipping

[@bonkeydollocks1879]

You saw that video too uh?

[@andrewcheatle4691]

Just used 2 good quality hose clamps on the split socket today thinking how clever I was - and they both split😭 Back to square 1

[@joebklyn8458]

Great video, you kept your cool nicely. I go outta my mind when stuff goes south.

[@Phoenixrising8313]

I had Stuck Sensor. I ran truck 15 mins hit with penetrating oil left truck running removed with open end wrench 22m. Out it came.

[@Winters186]

That worked. Ty

[@christopherkerr2254]

Worked for both of mine thank you!!!!!!!!

[@captaintor7920]

...And that's all there is to it! LOL. Lots of work. I'm still trying to get mine out. It takes awhile. Good job. This takes persistence. Thanks for the video

[@jamesj.litteriojr.433]

Very Nice way of adapting to the problem!!!!!! 👍

[@marctirone3266]

put a small radiator hose clamp on the socket to keep it from spreading or breaking. instead of a cumbersum c-clamp

[@labradormcgraw]

Your video really helped. Thank you. All the best from London

[@audiofrik]

Thanks for an excellent video. I will be changing my sensors next weekend.

[@petset77]

Excellent suggestion with the clamp over the split socket, so it won't separate while removing. ....The torque spec on my wife's Subaru for reinstalling a new sensor is 14ft/lbs. The stiff hand tightening is certainly enough.

[@kevinh7850]

Cutting the top off the old sensor since it is going in the garbage and using a regular socket is so common sense that I didn’t think of that. But at least the split O2 socket is handy for putting the new sensor in. Really appreciate the video.

[@Sandysand701]

A Good tip also is to give the sensor a good scrub with a wire brush before spraying it with penetrating oil, I use a wheel wire brush in a battery drill, works a treat

[@Hootyhoo-jq9vq]

Thank you filming this

[@anthonysaponaro6318]

Heat Gun? You couldn't possibly be serious ? A trip to the Deeps and a good ol bottle of MAP gas

[@ortiztaxi1055]

Exactly. I never used a heat gun. He must be newbie. Sorry my guy but being smart is also being safe than sorry.

[@Darksyne]

And that's why you always put copper anti-seize on the threads of your new O2 sensor. Never know if it'll ever need replacing again.

[@jim9win]

Thank you for some good ideas there's

[@TheWilferch]

Should have maybe started with a flare nut wrench...and the more-precise and tighter-fitting 22mm size vs 7/8" can work to your advantage too. Also...when you "hammer" on the wrench.....you will get more vibration/impact on the nut through a normal wrench....don't do it with a ratchet as 1.) it won't transmit the impact as well and 2.) hammering on the ratchet can damage the ratcheting mechanism if you want it to work for you again later.

[@hyzercreek]

22 mm is slightly smaller than 7/8 and is therefore less likely to round the nut. Use 22 mm if you can.

[@billsellgren9885]

You can buy an oxygen sensor socket,they have a short one an a longer one.They have a cut out in the socket for the wire on oxygen sensors to go through.I like to take a hose clamp and I snug it up around the socket.I don't want the opening cut out for the wire to expand on me while,I'm trying to take out the sensor.If you didn't have any luck with the oxygen sensor socket then, try a 22mm socket.If your going to replace the oxygen sensor,then cut off the wire on the bad oxygen sensor.Use a 22 mm socket works better than a 7/8 socket,and a breaker bar,if you have the room.Tap lightly, with a hammer on the breaker bar, to break free rust and free up the sensor.You might,have to apply some heat if it doesn't loosen up for you.Definitely,use some gloves to save your knuckles. Once you get the bad oxygen sensor out, apply some anti-sieze to the threads of the new sensor.Clean around the opening before,you screw the new sensor in.Tighten the new sensor the best you can.Put some dielectric grease,on the oxygen sensors wire plug before you plug it back in.

[@randypond7499]

6pt. Or 12?

[@GA-tl4iy]

Thank you so much for video. QUESTION: Is that Upstream or Downstream Oxygen sensor ?

[@ijam_hunter_fishinghidaniz186]

Thanks tips Friends...always done after use hot gun anda wd40...follow this Friends guys...good tips.

[@richardhill2379]

After you disconnect your wire, take a smal hammer and tap around the face of the nut body and surrounding area, then get your split O2 socket, put it on the sensor then then get your breaker bar. Apply a little tension while striking it lightly with your hammer for about 5 min. or so then give it what you got, when it cracks and exposes some threads, stop and spray some lubricant on exposed threads. Let it sit for an hour. Then come back and finish taking it out.

[@PandaPlusMarv]

Cutting the wire if you have a brand new O2 Sensor on standby is worth it so that you can get the annoying wire away and attack the Sensor with different sockets. Ended up heating up the car for a while, blasting it with PB Blaster more than once (different intervals every 15-30 mins), used the two wrench method to get extra leverage (this worked better than a breaker bar apparently), and out she popped.

[@knottreel]

I've noticed that penetrating fluid seldom penetrates.

[@rl4889]

It never does.

[@orionred2489]

Mix 50% automatic transmission fluid (non-synthetic is better) and 50% acetone.

[@hyzercreek]

@@orionred2489 won't get past the crush washer

[@Falwiz]

I agree I’ve used various types of penetrating oils for over 45 years, every time I manage to free up the nut, bolt or o2 sensor the threads are completely dry. Even after soaking for days.

[@rogeruk4291]

Plus gas product penetrating fluid 👍🏻

[@catslivesmatter1268]

Yes six point socket and having the sense enough to cut off the old one with a breaker bar will work every time 😂

[@nicktsoulli1796]

I hacksawed and broke off the end of the sensor off leaving the bolt behind, put an 6 sided impact socket on and used a big breaker bar and blow touch to heat up exhaust pipe. Also when it went I used more penetrating oil ( WD40) worked that in before putting unwinding the sensor out a bit more to prevent scoring and damaging the threads. bit excessive but thats what mine took. I was only going to round off the bolt with these O2 sensor sockets vs a full socket. Just make sure your sure that the sensor is at fault before you go crazy like that. Do the diagnostics on the broken sensor.

[@troyarmstrong624]

I got to replace my o2 sensors on my s10....I'm dreading it so much but has to be done the po has never changed them so I know it's gonna be simply stupid to crack em loose lol and it's a 2000 😂 great vid

[@TomMack530]

WhT year /model / make is the vehicle you are working on???

[@liamearnest315]

Time to attempt this on my 22 yr old 4runner that has lived its whole life outside in a very humid area.

[@marbf50]

Try a small pipe wrench to remove the 02 sensor

[@rfcasey]

An old 7/8 or 22mm box wrench with a notch cut into it for the wire may prove to be useful or even better a line wrench. If it is still stubborn, you may want to consider pounding the wrench with an air hammer that is equipped with a smoothing bit. By-the-way may I suggest using a hose clamp to better secure your O2 sensor wrench.

[@Exekutioncro]

why you need the wire? youre changing the sensor, just cut it and put a socket over it. Its pretty easy

[@rfcasey]

True if you are disposing the O2 sensor.

[@BLACKLACDTS]

Thanks man you gave me an idea and it worked. Cut that bastard and get the socket and big Dewalt impact on it and out in a second.

[@MrTruckerf]

You have more room under there than I do!

[@BLACKLACDTS]

@@MrTruckerf I went through the wheel well. Didn’t have much room at all but just enough

[@BLACKLACDTS]

@@MrTruckerf what vehical you have?

[@user-ms8xp4dx2k]

If you're replacing O2 sensor just cut the wires at the sensor and use a 6 point box end wrench

[@cynthiab4004]

So the mechanic tried to replace the O2 sensor and said it was welded to the manifold. Why would it be welded to the manifold, and does anyone have any idea how to deal with this please?

[@rytoniowendolini2793]

I'm trying to do the upstream sensor in the back on a bimmer. I bought a torch and I can't angle it as it just goes right out. I can't tilt it enough on the angle I need to heat it. No oils are working. This really sucks. Hard to reach and move around in there. I could take the whole dam car apart just to have the room I need. I burned it with some cotton believe it or not and carefully so. It melted in part of the sensor. LOL. But not where I needed it too. What kind of tool did you use to cut that? I need something really small just like that.

[@davidarents9000]

I love the ingenuity in the video. I have an upstream sensor in a 2005 Toyota Highlander and tried everything (heat, PB Blaster, special tools). Wished I owned breaker bar as that might have helped (no room to pound in tight space). Nothing worked. After two days of crawling under the car, had to wave the white flag and take it to a mechanic. The worst one to get to in this vehicle (Bank 1 Sensor 1). It is up on top of the cat converter so nearly impossible to get to with a hydraulic jack and jack stands. Afraid I would ruin it if I started cutting it out (didnt see this video until already took it in). This gentlemen has way more patience than I do, awesome fix.

[@carlosk8103]

Something that makes this even worse is many are in place with limited access you are upside down at odd angle can't see what you're doing (so doing the job basically blind) and it's stuck like hell like on here... Good tip is some kinda of lubricant let it set before you start....

[@MrTruckerf]

Having a massive supply of cuss words comes in handy. I even invent a few new ones as the situation if the situation calls for it.

[@bobmarleystoe]

you made a right arse of that mate dont hit ratchets with hammers you bend the teeth and then they break .you put a spanner over the sensor and loisen that with a hammer.

[@mjay6567]

I don't imagine an electric heat gun getting hot enough.

[@gameoflife7235]

It's possible; it couldn't create a large enough temperature differential between nut and sensor. A torch would have been much better for directing high heat to only the nut before getting wicked to the rest of the exhaust and O2 sensor.

[@robertmack7116]

@@gameoflife7235 Heating is not actually about expanding the outer thread vs the inner. It’s about making the whole assembly expand and contract- to make the parts move relative to each other. Even a micron of relative movement will help break the bonds that are holding them together. Get a hot torch and heat the hell out of it. Heat gun won’t make it, there’s too much metal pulling the heat away. You have to burn.

[@THOMMGB]

Nice job. I'm looking at the threads and it doesn't look like any penetrating oil got on those threads, it was so tight. Is that correct?

[@dvader3000]

Oh wow,you are a genious.

[@MrTruckerf]

You are correct, Sir!

[@nhactanthanh]

Any tips and tricks are good but before start applying any, take a careful visual look then apply one that you feel appropriate. Cut off the stubborn sensor and MAP gas works but you will have very hard time and dangerous to put socket on and breaker bar when the metal is red hot, it is even much harder some cars have tight space. I put socket and breaker bar before to see if I can and if you can't then must get it done first before and leave it then start heating the exhaust. Believe it or not, if you do it vice versa then what's the point to heat it red hot when can't put on the socket and breaker bar? For cars in the snow regions, salt and water make this even worse than the ones in the dry regions. If the sensor with severe bad rust and cars are 15 years old then O2 socket with pipe clamp never bulge it (thin wall 7/8" or 22mm socket and pipe clamp are a joke just like in this video), it just round the O2 nut and you have less chance and more time consuming to apply the next tip. My experience is never, never try too hard if O2 socket and pipe clamp can't bulge. More you do, worse the situation will be. Use your eye ball and evaluate the situation then use one way may work, if not, go to the next level of removal, stop worsen the situation. O2 sensor socket is just for the easy and not too old and rusted cars. Wasting $ and too much time with O2 socket and never work are very common while just use a simple impact socket do the trick, thick wall impact socket is recommended (it works amazing). I've done some cars that O2 sensor (downstream) just like welded to the exhaust and learned the pricey lessons. When the O2 nut is damaged and none of sockets work then I used impact hammer to bulge and plumber wrench to remove (if there is enough space), use impact hammer to bulge on 2 edges of the nut and sometime it cracked loosen to use pliers to remove it. Of course, if someone hands you a car with rounded O2 nut he gave up then it's the time you could use your magic wand.

[@notorious1ace]

Hi, long time ago, but you probably should have used a map torch to heat the sensor even though it looked like you could have got it with the breaker bar but you gave up too soon on it.

[@yourlocalalexis4578]

heat it with some propane, acetylince or those new magnetic heaters, and of course, lots of patience, because you dont want to break o2 sensor in that fitting!!

[@ortiztaxi1055]

Why not just use a breaker bar to begin with along using pb blaster? I have used just that in situations like this even with tools from harbor freight.

[@songsfromthelord888]

Excellent video Game of Life! Thank you! Remember that God loves ❤️ you, and that life is not a game but a serious tryout for eternal life . . . Heaven or hell, - the choice is yours . . . it's a choice that we all have to make . . . to love and serve God - or not. Again it's a choice that we all have to make for ourselves - no one else can make it for us . . .thanks again for your help. 🙂

[@gregorymceaddy8884]

Always wear clean latex gloves if touching the tip of the sensor...it runs on 0.5 volts and the smallest contamination will not let it read right..your better off using a 22mm box end wrench than a socket to break it loose...

[@charlieakin8074]

To remove all bolts rusted nuts etc. just tighten it a crack to loosen that bond then remove, they come right out or off.

[@CentralCanada]

Wow, that process actually works !? Will try it next time, I run into similar situation, as you mention ..... 🙂 Thanks .

[@robertnagy2456]

Breaker bar make wonder... with brake fluid on the thread.

[@marksavastano8339]

Been waiting three years too chang all four on my 1996 mustang GT, west they came out easy thow had to use a stand under the exhaust and lift up on the cat a we bit just to get in on the oassangers side first one the back ones were easy had help had a lift easy easy you aren't doing it easy from the ground fk artahere that's why they charge so much by the crook meen book hourly I put a fuel pump in also drove 90miles to use a lift Sunday special well took toatal of four hours for both a pro done the tank for me. 🙏🏻 Better fuel pump some whould need to get the whole assembly not a pro light went out until about 20miles on the way home only code itsthrowing is for the purge valve box thingy for the air pollution all in all it never trew this code ever that I've had her now sunk plenty heater core radiator water pump intake manifold knew raceing clutch and cable all within the past two years id of sold it quick if I did not like my 96 GT raggtop especially when she's right now now I'm upside down so too speak investing so much to get he tip top next move paint I hopes barring nothing gets I'll on my stang for a while love my car old as it is still ruu you from the start bet I win first 3seconds off the line to hats when I back way off and watch stupid mfkers try and floor there's by then pounding it 😂 idiots zoom zoom zoom getting dark out think I'll go take he out for a spin if I were Ritchie I'd still keep her thow I'd have a couple outhers also has a 93fox body sole it in like 06 still grabbed 35000 becose I offed to a friend and bought a truck trighttn engine best Ford truck as long as you can do certain thing s like plugs your self or dealer Ford dealersomeone whom works on thease on the daily then you ask who moonlights theyll be some person at Ford dealer that will tune up for couple hundred b leave that n done right no come backs capesh 🤣😂😆 ya fk you can do pay a bonus so there in correctly every shade tree thinks it's easy there not to tight your fucked they'll blow a plug so fast then you can fix that also thow ole beast whould go down the road like it's been gelded like a dog no faster then fivety five or it feels stressed n nopower theres a good truck too make it sound smooth in a dead cylinder small block of wood seven cylinders Bet ya 💰thow its a dead clynder it will still run not up to form thow like it's got a missed plug and it's a strong engine

[@WV591]

TU.. the most dreaded job in car repair. Penetrating oils only work on things that don't need penetrating oil. We fool ourselves by using them and is waste of money buy we fall for it every time and try. i had a stuck spark plug and spent two weeks spraying, and it never got on threads. had to use heat and punching torque.

[@gaskinsgarage4192]

First off you need to cut the wire off and start with a closed socket not that junk ass split socket that is only going to 100% strip it out. And second the two metals will expand and contract at different rates so it doesn't matter if you heat the exhaust or not all your looking for is expansion to break the threads or free the threads enough to hand loosen them.

[@ZBrink11]

I have now rounded the nut on mine and can't get a pipe wrench to grip. I've used propane 3 separate times to heat it for a full minute each time. It still won't budge. Advice?

[@gaskinsgarage4192]

Getting a decent set of vise grips that lock. And heat the thing up alot for more then a minute clamp it on as tight as possible and hope that it works. Otherwise you could take the exhaust off to cut and drill out 02 sensor till there is only about 5mm of thread left and used a flat head screwdriver to beat one end of the remaining threads in to remove remaining peace. If your to unsure take it to a good reputable exhaust shop to have it looked at not a chain store exhaust company. Or if your close to Indiana you could bring it by and I could get it out

[@gaskinsgarage4192]

And also if you had enough room you could weld on a closed ended wrench and let it cool down as to not prematurely break the welds

[@ZBrink11]

@@gaskinsgarage4192 Thanks! I have some good old, american-made vise grips. I will heat it up and try that. Unfortunately I am in Virginia so I can't bring it to you!

[@gaskinsgarage4192]

@@ZBrink11 just make sure the teeth are sharp and not dulled out otherwise it will slip.

[@donaldgibsonjr3448]

2 minutes 😂😂😂 sawsaw and boxend 22 wrench done 😂😂😂😂😊

[@beto1515]

Use a breaker bar and it will came lose faster and with less effort

[@spadestrump1112]

After some research, I've found the best possible solution is - 1) Spray Liquid Wrench penetrating oil on sensor/exhaust contact point. 2) Start car and run in idle for 8 min while sporadically revving motor up to 2,500 rpm. ( HEATS UP SENSORS THREAD CONTACT) PFF HEAT GUN LMAO 3) Snip wire in the middle between between exhaust and splice point under motor side 4) Grab 24 mm open ended Wrench and now you have access to using teeth side of Wrench. 5) While loosening, Spray Liquid Wrench and go back and fourth to coat contact with lubricant. 6) With all your strength, Mustard a Fart in the palm of your hand and throw it at the person closest to you while Shouting (Fart Frisbees) 7) Bask in the glory of your masculine scent The end

[@MrTruckerf]

I'm sorry. I wasn't paying attention and missed the most important part! When should the other techs toss the firecrackers under the car and then shoot the fire extinguisher on the mechanic?

[@charlesphillips1642]

Hose clamp not vise

[@ortiztaxi1055]

Please everyone: Do not use any heat on those sensors. Just use a breaker bar with the oxygen sensor socket or a wrench that fits that sensor. You are risking more damage to a vehicle if you do not know what you are doing and heating the bottom of that sensor will take forever. The only time you can get away with heating up car parts is while working with suspension.

[@jeffreylumbar4937]

Best method is to heat it up then hit it with a ice cube makes the threads retract

[@jimmykulik3438]

Just heat it red hot with a torch and quench it 2 or three times. It will come right out done

[@stonestitt5714]

I broke my sensor the whole piece came off will i have to chnge that whole exaust out

[@MrTruckerf]

No.

[@danpettis1675]

actually the penitrating oil will do nothing because of the crush gasket it won't reach the threads

[@yourlocalalexis4578]

lol, the vapors supposedly will get in there...lol

[@MrTruckerf]

That's what she said.

[@Mr.Atwood]

Haha I just broke that same socket trying to loosen the downstream sensor

[@pingpong9656]

How about start the car to get it hot instead?

[@MrTruckerf]

Battery is dead.

[@danpettis1675]

auntie sees

[@JimJones-om9rf]

Mine has become rounded and I don't know what to do

[@MrTruckerf]

Call 911!

[@minbannister3625]

It was 1997 when Ford products turned to shit.

[@MrTruckerf]

True!

[@ElphinAndy]

Much earlier to be fair. Bought a '69 Mustang and never bought another Ford.

[@chrismorris1750]

Is that bank 2

[@gameoflife7235]

Yes this was Bank 2 (Drivers side). I changed Bank 1 a while back and it is a little tighter to reach.

[@jamesradcliffe3985]

heat gun isnt really going to do much plus that heat will be going all over. I also bought a 7/8" O2 socket just like yours and it was way too sloppy to use. I cut half of my sensor off and used a 22 mm socket.

[@tictacawsome2119]

that heat gun didn't do shit

[@Align700nitro]

liquid wrench every 2 days for a week, wrenched it off like a normal nut.

[@MrTruckerf]

I say Bullshit! Not about what you claim- I believe you. I just like saying Bullshit. Bullshit! Bullshit! Bullshit!

[@raulmunoz2022]

Hahaha

[@j.d.garcia2757]

Soaking 24-36 hours in a50%water and 50%white vinagre ! Easy 👌

[@mike_AD]

i thought of that too... i have rags with penetrating oil wrapped around it right now... i may switch over to vinegar now!

[@pingpong9656]

Please give some details - I would love to try it.

[@mike_AD]

@@pingpong9656 i personally sprayed it with "wd-40 Rust Release Penetrant" (a specific type of wd40, not regular, bought it at harbor freight) and then soaked rag in white vinegar and wrapped it around the sensor, left over night. next day i used socket wrench and breaker bar, and it broke free. Good luck

[@ryann9674]

Anyone notice the cat smoking after using pb blaster I know that it maybe the cause from spraying it not sure if I should let my car run and let it burn off or not.

[@robertboykin1828]

get LIQUID WRENCH on it a.s.a.p.

[@drew-shourd]

...@3:48...hahahahahahahahahahahahahahahahahaha.....first showing what to do, then say it's what NOT to do....these are a bitch fer sher. I have a 2000 Cherokee, it was crazy hard...tight fitting socket, heat, lube, repeat, repeat....then finally...

[@patrickperry6945]

I have a ‘99 GMC Safari van the sensor is in an impossible spot to access. I’m using one of those small o2 sensor wrenches to get the sensor out of there. I have used heat, 32” breaker bar, and an impact wrench. Won’t budge. Never see anywhere anyone works on one of these vehicles. Very disheartening. 1 bank sensor is really a piece of cake. 2 bank is impossible.

[@mauricioh6716]

Blessings, John 3:16. Jesus loves you. Thanks for the video.

[@user-lc6de8rh8r]

These oxygen sensors are a bitch to come off😂

[@rogers906]

This method has worked for me 90% of the time. 1.use a cold chisel to tap on the rusted nut and scrape off all loose rust. 2. Use a steel wire brush and make sure nut is clean 3. Spray liberally liquid wrench or pb blaster. Wait 30 minutes. Using a claw type sensor socket give it a couple of good taps using an air hammer. If it begins to get loose use a breaker bar. If not heat up the nut and try again and again. I have had a situation once or twice whete the bung came right off because the rust had eaten through the welding. You will need to reweld a new bung.

[@larry459714]

haha lol all my attempts have failed.

[@jacjumpin7471]

You are nutz Oil will not penetrate into threads

[@robertrose3068]

I saw another video where someone used a hose clamp on the o2 socket to keep it from opening up. I would cut mine off if I knew it made it this much easier to remove.

[@frederick6008]

Step one: buy a O2 socket. HF has them for $8.

[@davidhimmelsbach557]

They are useless for removals. They are intended for installations. Only occasionally will a trick socket be required. See Scotty Kilmer's video. Cut the sensor as short as you can -- without getting ridiculous. You still need the base. Then, use heat + candle wax + a 6 or 12 point socket -- shorter is better -- and work it lose/tight/lose/tight -- by hand, by breaker bar, by hammer -- just tappa tappa. Don't go overboard with muscle. The fitting can't take all that much. Attempting to use a trick socket is what is doing everyone in.

[@hyferCOM]

Worst tutorial

[@deh5860]

Thank god we are moving to electric cars. Don't have to deal with all these non sense.

[@imaouima]

That's funny.

[@johnnybethnalgreenkent8747]

Turned off after i see spray crap bro

[@mikegrazio5376]

you know that heat gun is silly. that absolutely did nothing. When people tell you to use heat, they mean an oxy/acetelyene torch and get the surrounding area cherry red.