Problem: Code PO125

2000 ZX2, 60K miles; “Service Engine Soon” light came on.
Went to Autozone, and they scanned it, and came up with code PO125: “Insufficient Coolant Temp for Closed Loop Fuel Control.” They told me this meant I had to replace the temp sensor in the vehicle. Was this correct?

If it is correct, where is the thing? For the life of me I can’t find it.

If it isn’t correct, what do I need? Thanks. This has been bugging me a lot lately, and I fear my gas mileage is pretty low as a result of this.

The defenition of the code is correct, dont know what it means.

Is that the radiator temp sensor? If it is, it is located at the bottom of the radiator. I would double check and see if that is the Temp Sensor they are speaking of.

If it is, there is a replacement that you can purchase It will turn on the fan 15 degrees sooner.

Relax guys. I get that code all the time since I’ve had that ZXTuner low temp thermostat, basically if the car doesn’t get to 210 degrees it will give you that code, and especially if the climate you live in is cold during the winter, you will often get that code. If you want to replace the thermostat anyways, its just to the right of the exhaust manifold if your looking at it from up front. Follow the upper radiator hose to the black box looking thing, the thermostat is in that housing. Careful not to crack the housing its made of plastic. I believe its 4 small bolts holding it in there, havn’t changed mine in 2 years.

This indicates one of two problems.

Like he said, the thermostat is sticking and needs to be replaced. This can be determined by watching your temp gauge in the car. The ECT sensor and the ECT sender are two different devices. The sensor sends data to the PCM, and sets a code if not right. The sender sends data to your gauge. They function indepedant of each other. So, if your gauge reads in the middle when warm, normal, then chances are, your ECT sensor is bad. The thermostat is cheap and easy to replace and it probably a good idea to replace it anyhow. The ECT sender is right on top of the thermostat housing and has a two-wire plug going to it. The earlier models have threads and screw into the housing. The later models have a clip that holds them in. So, if you have to get a new ECT sensor, make sure you get the right type, screw in or clip in. Running in open-loop lowers your fuel economy and can cause a ‘rich’ condition and decrease your plug life and cause carbon deposits to build on the cylinder walls and valves. Also, the extra fuel can clog your catylitic converter. This is a problem you should fix as soon as possible.