Symptoms of a Bad Coolant Temp Sensor (2004 Impala)

[@bbracing3925]

Holy cow, you just described what I'm dealing with in my 92 Lexus SC300 that is also at 200,000 mi. I'm also smelling the sweet exhaust smell, erratic mid range temp. idle issues. Stumble/ fuel cut? (Punching the gas to merge). It also kind just feels sluggish. I've "scanned" it multiple times (T1-E1 pins) & no related dtc codes for it or anything leading to it. But I have a new one because I've been sort of suspicious of the temp sensor. Hearing your test drive observations makes me feel hopeful haha. It can get annoying sometimes with the older OBD1 systems as they age. Thank you, I'll let you know if this applies to my Lexus or not.

[@paulhaines5755]

Glad to help! Hopefully that is your issue, too as it's pretty cheap and easy!

[@bbracing3925]

@@paulhaines5755 Unfortunately my research into the before mentioned issues will continue. Silver lining though, my sensor was bad. It was starting to burn up inside the sensor (between the plastic and brass body of the sensor) it was also brittle. It broke in half just touching it. It made it much easier to remove. The sensor is not in the easiest location to see or get to on a 2JZ-GE.

[@paulhaines5755]

Hmmmm - so still running bad I take it? I'll look into the cat, next. A rich running vehicle can ruin/foul/plug the cat in time + also give you smelly exhaust.

[@paulhaines5755]

Other simple things to try - have your injectors professionally cleaned at the local lube shop. It really does help. I've had it done a couple times over the years and notice a real difference in how my car runs. Clean your MAF with approved cleaner only. Make sure you air filter is clean. Make sure you do not have a spark plug wire that is arcing out somewhere on the engine. Inspect it in the dark and listen for it. Remove upstream O2 sensor and run it. If it improves noticeably you likely have a cat issue.

[@jt8280]

Hi, Paul I have the same engine, no smell from the exhaust but my temp gauge is always at the mid level when driving daily and does not kick in the electric fans. Could it be the temp sensor ? Thanks

[@paulhaines5755]

YES I believe a bad or flaky temp sensor can cause issues with the cooling fans. Bear in mind I'm no pro - just a guys fixing my own stuff the best I can with simple tools so I might be wrong. Here's how I understand it: The CTS gives resistance info to the ECM. Resistance changes with temperature. The ECM controls many many things that affect how the car runs. Additionally, the ECM energizes relays that turn the cooling fans on and off. I'm pretty sure that if you disconnect the CTS and start your car, the cooling fans will come on as a fail safe designed into the ECM system. If they do not, you have an issue with a fuse, relay, wiring or the fan motors themselves. Check the basic stuff first; aka fuses, relays, wire connections! FYI the fans on my car rarely come on unless it is hot outside/summer season so I did not recognize this as a problem when my CTS was bad. All I noticed was poor performance and the things discussed in this vid. Fast forward almost a year and the car still runs very well - no issues.

[@Pathfinding-earth]

I have a Nissan, but it describes all of my issues, so Im going to get that and see what happens, I also have that code but for Nissan is P0115. thanks for this video.

[@paulhaines5755]

Glad to help! Let us know what happens.

[@jjano2320]

Do you have to drain some coolant out?

[@paulhaines5755]

When I did this job on my car I lost no coolant. The car was fully cold of course.

[@Djayhasapikachu]

How do you find the temp sensor on let's say a 04 Malibu V6

[@paulhaines5755]

I'm not sure. On my engine it's under the throttle body.

[@jim12186]

did your dash temp gauge show cold even when hoses were too hot to touch?

[@paulhaines5755]

No gauges and such seemed to work fine.

[@MrMDee-si1bz]

Thanks for sharing! Paul! My Montana has the same %^*% symptoms! I’ll try that! 👍🏻👍🏻

[@deedillz]

I think I’m going thru the same thing but mine overheats when the ac is on but I’m getting the p0125 code

[@paulhaines5755]

Hmmm that's interesting. I'm not sure how a CTS ties in with your AC. I haven't had that issue before and mine wasn't overheating but it is cold here and I haven't used AC in months! I bet if it was hot I might have had that same issue as you. So maybe the CTS tells the ECU to turn on the radiator fans? If your fans never come on that's prob why you are overheating. AC condenser creates heat and the fans need to pull it off. You might have to research it some more to see if your CTS is something to replace or test.

[@deedillz]

@@paulhaines5755 so your thinking that my radiator fans have been the fans that’s used? And not the actual ac fans? Because I didn’t noticed once that it was fans running one day when I had turned the car off

[@paulhaines5755]

I'm not 100% sure what you are asking. Please remember I'm no mechanic by any stretch of the imagination but I'll offer some help: my car has two electric fans behind the radiator. They come on when the vehicle gets hot and many times when the AC is running. The AC condensor will cause more concentrated heat in front of the radiator so this heat needs to be pulled away by the fans. If your fans are not coming on, there is a good chance that is why you are over heating. A bad CTS could be the cause of these fans not coming on but I can't be sure as I've never had issues that were in conjunction with my car over heating.

[@deedillz]

@@paulhaines5755 it was indeed the sensor my 04 impala is running like a champ check engine light off

[@paulhaines5755]

Great! Good to know and good info that it's tied to the fans as well!

[@bruteman45]

Did you have to replace the throttlebody gasket??

[@paulhaines5755]

I didn't and it's fine.