P0128 - 2002 Sl2 - Help

[TXSaturn02]

OK guys. Need suggestions and your HELP. On the way home from work yesterday my Service Engine Soon light came on - first time EVER. I'm now at 84,018 miles. Took it to the Autozone and they gave me the code of P0128. Meaning I need to either:

1) Check Coolant - seems fine and temperature is fine also.
2) Temperature sensor is bad.
3) ECTS is bad - Since I have a 2002 I should have the brass one, but I've never looked.

Should I just go to the dealer and get the Temperature sensor? Any idea of what that part number is?

I'm at the Autozone right now on my laptop. Will leave as soon as I post this and head to the dealer. Will check for messages then.

TIA

[richpin06]

Another thing that will set off a po128 is a defective thermostat.I would pull the PCM B fuse to clear the code to make sure its a hard fault.

[TXSaturn02]

Originally Posted by richpin06

Another thing that will set off a po128 is a defective thermostat.I would pull the PCM B fuse to clear the code to make sure its a hard fault.

Thanks Rich. I'll try that before buying the thermostat. Something the parts guy here mentioned that if the car is running and the coolant in the resovoir (sp?) does not move around after a while, that is an indication of the thermostat going bad.

Where is that PCM B fuse? Under the hood or by the passenger seat? The service guy here at the dealer stated that it was very unusual for a thermostat to go bad on a 2002. He said he only saw a few of those. I'll go do the fuse thing right now.

Thanks.

[TXSaturn02]

Thanks Rich! You Da MAN! I found the PCM B fuse and had to pull hard to get it out. In the process, I lost the darn thing somewhere in the engine compartment. No biggy. I just replaced it with a spare one and started the car and bada bing! The Service Engine Soon Light is gone! I'm about to leave the dealer. If ya don't hear back from me, I'm good!

[nbdew002]

Originally Posted by TXSaturn02

Thanks Rich! You Da MAN! I found the PCM B fuse and had to pull hard to get it out. In the process, I lost the darn thing somewhere in the engine compartment. No biggy. I just replaced it with a spare one and started the car and bada bing! The Service Engine Soon Light is gone! I'm about to leave the dealer. If ya don't hear back from me, I'm good!

WHere is this PCM B fuse?

[madpogue]

Originally Posted by nbdew002

WHere is this PCM B fuse?

In the underhood fuse box. There's a guide on the underside of the cover, and in your owner's manual.

[keautocenter]

I also have 2002 SL1 with a p0128 code. The temp gauge is just over 1/4 when driving, but it has plenty of heat coming out of the heater. I really am not sure what to do first, the thermostat or the ECTS or ECTS wire harness. If it was 2001 or older, I would do the ECTS or harness first. With the coolant getting up to temp, I have a hard time believing that it is the thermostat, but then again, the gauge is just barely over 1/4. What do you think?

[TXSaturn02]

Originally Posted by keautocenter

I also have 2002 SL1 with a p0128 code. The temp gauge is just over 1/4 when driving, but it has plenty of heat coming out of the heater. I really am not sure what to do first, the thermostat or the ECTS or ECTS wire harness. If it was 2001 or older, I would do the ECTS or harness first. With the coolant getting up to temp, I have a hard time believing that it is the thermostat, but then again, the gauge is just barely over 1/4. What do you think?

It is most likely the thermostat. After pulling the fuse, it reset the code. But after a few weeks, the code returned. I replaced the thermostat and the code has been gone ever since... Replace it - it is a cheap part and if you have the right tools, not that hard to do on your own.

[keautocenter]

I wanted to let everyone know that I did change the thermostat and it solved the problem. I'm grateful for the help that everyone offered.

[adventureoflink]

Good for you keautocenter! just goes to show what one can accomplish with a 3/8" drive ratchet and a 10mm deep-well socket (IIRC)