CHTS Sensor Upgrade/Relocation Z31

NOTE: Recently there has been a lot of confusion regarding the relocation as the new sensor for the pathfinder is not the same size thread as the intake manifold. Ensure when you purchase your new CHTS that the picture looks correct and then before installation check the new sensor against the plug/sensor that you just pulled out! There are some sensors that are too small and do not fit.
This is a relocation you can do for the CHTS sensor on a vg30 engine. The CHTS sensor is known for going bad and causing a lot of problems. This swap makes it easier to access and also uses a sealed "wet" sensor from a '95 Nissan Pathfinder which is more accurate than the original Z31 "dry" sensor.
Link to CHTS I used: www.rockauto.c...
Harness from: nissanpartsdeal.com
Also check out our website at: TheZGarage.net
I am not a professional mechanic and the methods described in my videos are solely based on my research and intuition. I make mistakes and when I do, I try to point them out so others don't make the same mistakes. These videos are meant only as a description of what I was trying to do and how I went about doing it. Before attempting any service on your car, conduct your own research and use common sense.

[@bobluhrs]

I finally did the upgrade of my 84 300zx turbo to the 95 nissan pathfinder temp sensor mounted in the old injector cooler temp sensor switch port in left front cylinder head area using the 300zx harness for it. I replaced the automatic injector cooler fan when it died and I couldn't find the parts, with a windup electric timer like you find on bathroom fans. This new sensor made a huge difference, and the car runs so much better, even seems to get better gas mileage(?). Now if I need to check the harness or spray the contacts with cleaner, it is SO easy to do. Replacing the sensor is also very easy now. I think the new sensor is better designed, doesn't rotate or wobble around like the old one did, too. So MANY thanks for this simple hack, it's almost like driving a new car. :)

[@bobluhrs]

I made an offset wrench to grab the CHTS, then cut a piece of shroud away and made sheet metal plates with screws in them so I can remove some of the plastic shroud while working and easily replace when done. I do the thing without any real disassembly at all, and no butchery of the stuff in the way, either. To make the wrench, I took a 3" (3/8 socket) drive extension and welded it offset to a deep socket with a cutaway to clear around the stuff in the way; it works fine to tighten and loosen the sensor, then I use a finger (takes 5 minutes) or piece of rubber hose, really fast to wind it out and back in. Changing the sensor takes about 15-30 minutes, depending if a cute chick comes by or not. Bob

[@wagons69]

i picked up an 85 300zx for $800 and this seemed to be the only issue aside from cosmetic stuff thanks for the video

[@realisticthinking3019]

i got my 85 300zx for 1000, the build is coming together nicely. do you wanna swap numbers to see each others builds?

[@tylerchambers5312]

@xythos how did it run before you replaced it, I’m thinking this might be the issue going on with mine

[@wagons69]

@@tylerchambers5312 it didnt run at all when i bought it

[@nucleararkndjdk9476]

i just bought mine for 1400 about 3ish months ago and it still wont idle lmao

[@fan7asy]

when i pulled out the bolt , the thread size was a lot thicker than the tx18? wtf?

[@alexg9739]

Aren’t those sensors different thread pitch?

[@cooliecrewspeedshop]

Part number SU405 for AutoZone

[@ExCordeEnt]

Thanks for this. I'm getting ready to do this very upgrade. I found that I would set the timing on it and initially it would start fine. But after 5-6 starts it would become more difficult to start and eventually nearly impossible. I would unplug the battery, reset the timing, and then the car starts fine. This cycle keeps repeating. Im hoping that this sensor will solve this issue

[@emanuelorozco1439]

If I do the relocation, do I leave the original CHTS where it is and just put the wire on the relocated part? I’m just confused on what happens to the original CHTS. Because if I move it from one spot to the other I would have to block it off no?

[@TheZGarage]

The original sensor does not contact coolant. It is a "dry sensor" and reads the temperature of the engine block. So you can leave it in or take it out, it doesn't make a difference either way. I left the original in its place when I did my relocation because it's a pain to get to

[@emanuelorozco1439]

@@TheZGarage ok thank you so much

[@brettlevine4318]

So is this a Z31 wiring harness or a Pathfinder wiring harness?

[@TheZGarage]

The wiring harness is the standard z31 harness.

[@roselemay4416]

Did you end up doing this? Do you have an injector fan?

[@mmarchmonte88]

Will a regular Z31 chts subharness work or does it have to be a pathfinder sub?

[@TheZGarage]

Nope. Regular z31 harness is what you want to use

[@Dookieandsons]

I've got my chts sensor and sub harness but my sub harness does not have two plugs on it I'm going to have to utilize the end off of my factory plug and splice in this is a SMP standard connector part number SK 25 what I'm asking you is can I just cut the old one and pull it up from behind the timing cover and if so what do I do with the factory chts do I just leave it in the hole where it belongs and not use it anymore or what please let me know soon as possible also both wires on new connector are the same what do I do. Lol

[@fastlanegaming2000]

Alright I replaced it and nothing changed question 1. Does the ecu run on different maps when you do and don’t have this 2. My harness is set up a bit different how do I know which one to hook it up to 3. And what other problems could cause it to run so rich(maxed out on my a/fr gauge) and doesn’t move even under boost

[@TheZGarage]

I'm not sure if the ecu has different maps. This is a very important sensor so it takes whatever reading it can from this and goes with that. The CHTS should only go into one connector, it shouldn't be possible to go onto another one. And if it's really rich you could check the fuel pressure regulator to make sure its working properly. Use an online fuel pressure gauge

[@martinMIXER]

I forgot to ask last time but, do I need to bleed the coolant out of the engine in order to do this mod?

[@TheZGarage]

Not to put it in. And you shouldn't have to afterwards either. It shouldn't introduce too much air into the system and any air should bleed out when it runs. Not enough to overheat or anything

[@Z31Tapia]

So I just leave the original sensor on its original port?

[@TheZGarage]

Yep. You can take it out or leave it. It's a dry sensor so even if you remove it nothing bad will happen.

[@Z31Tapia]

@@TheZGarage Love the content man adn thanks for the help! Just did the timing belt as well and used your video as guidance. Awesome work man!

[@turbofedz8997]

So it's been a year since the MOD,how is it working? I never notice no coolant coming from the original location..I think it just measures heat rather than coolant temp..thanks.

[@TheZGarage]

You are correct, the original location is a try temp of just the engine block. The relocation is a wet location and samples the coolant temp. It's been reliable this entire time! No regrets!

[@ByronMartinez-l2q]

I cannot find the harness to save my life, please share the direct link to the part pleaseeeee

[@TheZGarage]

This is the part number. 24079-01P00 I usually get it from Nissanpartsdeal.com but you may find a cheaper option by doing a bit of searching

[@ByronMartinez-l2q]

@ I found it on eBay for about the same price! There’s seem to be hard to come by! Also, I need to change the valve cover gasket. Do you have a video for that?

[@TheZGarage]

I don't have a video for valve cover gaskets, although it is very straight forward. The passenger side should be very easy and all the screws are accessible. The driver's side is going to be a bit harder because the distributor is right on top of one screw so you may need a screw driver on a flexible handle to get it off. That also assumes you're removing the upper intake plenum since it sits ontop of everything.

[@ByronMartinez-l2q]

@ sounds pretty decent to do! Hey! Your channel is amazing as I am a brand new z31 owner. I got an 85 turbo with only 66k!!! Of course it has a few things wrong with it and hopefully I will make it look like yours!!!

[@antoniolemus1117]

Will this make your engine die upon start up if it isn't reading right

[@TheZGarage]

It's possible. Typical symptoms are difficulty starting and rough idle. I would also check the maf. Unplug it and see if it runs better. If it does, then that's your problem

[@cooliecrewspeedshop]

@@TheZGarage Could also be a vacuum leak if it runs better with the MAF disconnected, I believe the ECU changes the map and goes into limp mode. Had that issue with my 240sx when I deleted the emissions system!

[@danielstephens840]

Hi mate, can you let me know the part number for the subharness? Cheers mate

[@TheZGarage]

24079-01p00 I would recommend Nissanpartsdeal.com or ebay. Nissanpartsdeal.com has a great deal on it but I think ebay would ship it faster if that's what you're looking for

[@Zdirtyone]

Where can I get those hoses for the fuel regulator ? Mine are starting to crack

[@TheZGarage]

They're just regular 5/16 th fuel line. I recommend using fuel injection hose though because it's under higher pressure there and needs to be a better quality line. And use fuel injection hose clamps to secure them properly or they might leak

[@Zdirtyone]

What about the clear and orange one ?

[@TheZGarage]

@@Zdirtyone Those are vacuum lines. Any standard silicone or rubber vacuum hose will work. That hose is 4mm diameter

[@Zdirtyone]

Is there anywhere I can contact you in ? Im looking to replace the chts and also relocate it but I can’t find the plug w the wire that will be replaced

[@TheZGarage]

@@Zdirtyone Sorry, I had sent a reply but i guess it didn't go through. If you go to the contact tab at thezgarage.net that would be a great way or on instagram. If you go to the write-up section on thezgarage.net it has a written tutorial on the swap

[@Acarson87]

Wait so if you have the injector fan you got to undo a sensor? What does it have to do with the chts? I'm curious. And what years and models had the injector fan?

[@TheZGarage]

The injector fan sensor is in the port used for the relocation. If you do the relocation, you can't use the injector fan anymore. I believe 85 and up had the injector fan but only in markets that had a hotter climate. They weren't equipped on all z31s

[@roselemay4416]

@@TheZGarage I have a 1986 Z31 with the fan and even in the NE, if you run the car in the summer and get stuck in traffic, it's good to have the fan that cools the car. So, I won't be using this method. I'm looking into replacing the 86 ECU with an 87 ECU... have to do more research...I think it bypasses the 86 CHTS. But what do I know???

[@caitlinford4616]

@@roselemay4416have you found out any more info on the 87 ECU?

[@martinMIXER]

what could happen without the injectos fan temp sensor??

[@TheZGarage]

If your car was equipped with the injector fans, it will no longer run, however their effectiveness was questionable from the factory and modern gasoline is better at not vaporizing so you shouldn't notice any issues without it

[@martinMIXER]

@@TheZGarage even thou AZ is hot as hell? tbh im not even sure my car is equipped with them, its an 84 turbo with digital dash, thanks for answering so fast. i will try doing it your way, i like it

[@TheZGarage]

I don't think 84s came with the injector fans.

[@martinMIXER]

@@TheZGarage one less thing to worry about, thanks a lot man

[@cowboytanz]

So if I wanted to do this, would I have to remove my old CHTS that’s Under the timing and all that mess?

[@TheZGarage]

You don't have to. I didn't when I did mine but if you don't you have to buy a new harness which is another $30 or so.

[@FleetTech97]

That sensor you removed isn’t that for the temp gauge in car? How do you run your temp gauge now?

[@TheZGarage]

No, the temp sensor for the ecu and the temp sensor for the dash are two different ones. The one that feeds the dash is on the passenger side of the lower intake manifold. It has a single wire connected to it. The CHTS is solely for the ecu

[@georgegray6888]

could this simple modification would on a GLL (Digital model)? That's really my only concern.

[@TheZGarage]

I don't see why doing this would affect a gll at all. The sensor being removed is just for injector fans. Doesn't tie into the dash at all

[@markromero9195]

What’s your intake set up if you don’t mind me asking and any links for the filter or anything else you used?

[@TheZGarage]

Only real mod I have is my K&N air filter on the front. I got that on Amazon.com (sorry I couldn't find the link I used)

[@markromero9195]

The Z Garage is it just the filter itself or do you need a bracket to attach it or something?

[@markromero9195]

The Z Garage or did you just buy the k&n kit for like $210?

[@TheZGarage]

@@markromero9195 I bought the filter and it came with adapters for different size intakes. I think it only cost me about $45 total or something like that. Nothing crazy at all

[@DeathByClams]

Thanks for the video. I have an 86t and I think my coolant leak is coming from the old CHTS so I'll have to dive all the way in

[@TheZGarage]

The old Chts sensor is a dry sensor so it's not possible to leak coolant from that area unless there's a crack in the block. It's probably leaking from the thermostat housing or the coolant bypass hose. I would recommend replacing all of that when the timing is off since they're hard to get to

[@LAAUDI]

Do you know where the starter is located ?

[@TheZGarage]

The starter is on the passenger side of the engine. If you can jack the car up on the passenger front tire and remove it and look underneath, the starter is right on the bottom going into the bell housing of the transmission. It is usually a black cylinder and about 5in in diameter with a smaller cylinder to the side of it. If you go to rockauto.com and search up your car, it will show you pictures of the starter so you know what to look for.

[@demetrioreveles8017]

I have an 86 300zx. Besides a junk yard, do you know of any other place that would sell the electrical harnesses (internal & engine bay)?

[@TheZGarage]

Are you looking for the entire engine bay harness or just the one for the CHTS? There's​ a link in the description for the CHTS harness. As for the entire engine bay harness, 300zxpartsforyou.com might have some and many facebook groups will be able to get you one from someones shed or something that they have lying around

[@demetrioreveles8017]

I am looking for the entire harness.

[@demetrioreveles8017]

Sweet man I appreciate the help.

[@DementedDoodle2162]

Suprisingly enough advance auto carries the harnesses

[@rice_myhyundai816]

I did this and the ecu throws 13 and 33. After resetting the ecu and plugging back into stock location it was no longer throwing the code.

[@TheZGarage]

Where did you get your parts from? It's possible the new ones were faulty which is why it the code 13 for the CHTS circuit. And are you sure the other one was 33? I wasn't able to find anything for a code 33

[@rice_myhyundai816]

@@TheZGarage I used an orielly auto parts sensor. Don't remember the brand. I have an 88. 33 is fuel temp sensor. I plugged back into original chts. I'm having a different issue It is still throwing 42 exhaust gas sensor. I'm checking o2 and wiring harness today. Pretty sure it's related to that. I only tried the chts relocation because people kept recommending I check it.

[@TheZGarage]

Did you ever try running it with the relocation to see if it ran any better? And I'm looking at the XenonZcar page and it's saying 33 is the egr circuit and 42 is the fuel temp. One thing you can try is unplug your 02 sensor and see if that changes anything. It goes into a closed loop when you do that and just runs off the fuel map

[@rice_myhyundai816]

@@TheZGarage lol got it backwards. I was throwing 13, 33, and 42 after driving it with the relocation. It ran the same as it did with it plugged into the original chts. It just threw 2 extra codes. Fuel temp sensor has a very coroded looking wire harness. Gonna fix that and see how it does before I change the fuel pressure regulator.

[@TheZGarage]

The fuel temp sensor doesn't change anything in the ecu tuning so I would just ignore it. Similar to the egr, that would just effect the emissions, shouldn't hinder how it runs. What I would suggest is to try unplugging the maf and see if that solves your problem. With it unplugged it will only rev to 3k but if the maf is giving a bad signal it can make it run pretty bad. That could at least narrow the problem

[@FleetTech97]

Hey man what are dimensions of the cone filter you have on? Just trying to find a universal one I can put on my car

[@TheZGarage]

I don't quite remember but it is a K&N, maybe 10 inches long, and has a max diameter of like 4 inches but comes with adapters to go down to the stock intake size (3 inches if I remember correctly)

[@mikegruizinga6875]

Old sensor is 1/4 NPT and pathfinder is m12x 1.5. So wont this leak?

[@TheZGarage]

It's been working perfectly for me for a few months now. The thread fit perfect and wasn't lose so I believe they're the same thread

[@alrui]

What did you end up doing Mike? I also noticed the plug in the manifold is .040" in diameter larger and has a different thread than the TX18 Pathfinder sensor.

[@mikegruizinga6875]

Im using a GM coolant temp sensor and a standalone ecu

[@alrui]

@@mikegruizinga6875 I "assume"the GM sensor had the correct metric thread?

[@alrui]

OK, the correct adapter to do this right is actually M12X1.5 Female to Pipe BSPP BSP 1/4" Male. The engine side has a British pipe thread!

[@Dookieandsons]

I've said it a hundred times man I really don't mean to bug you but you no more about certain things than I do I am computer illiterate I'm pretty good with wiring I'm good with electrical and mechanical I was just about anyting I'm just computer illiterate as a MF LOL thanks again for all your advice and help my car is almost where I want it but you know what I would really like to do is do the rear mount Turbo I know I've said it it seems like then I wouldn't have to have the turbo manifold or the crossmember or the alternator on the other side and they say you don't need an intercooler because it cools from the ambient temperature of it having to run back up the car plus I think that turbo looks mean as hell sticking out the back of the car problem is I don't think there's enough room under the Z car to do this I would really love to have the patience and the money and the help to do mine the way yours is

[@iiXtcy]

That wire harness is no 60+ $ smh….