[ventport]

I just had the head gaskets, water pump, timing belt and kit and serpentine belt, and heater control valve replaced on my 98 Catera. It runs fine cold, but after warming up it sets the check engine light with the code PO115 "engine coolent temperature sensor circuit". The car restarts hard when hot, with lots of cranking, and when it finally does start it idles around 1200 rpm. If you run it long enough with the air conditioner on it overheats, but the cooling fans do not come on. I'm thinking we didn't hook up a sensor or hooked a vacume line up to the wrong place. It also makes a growling noise coming from the front of the engine when it runs a while, but the noise comes and goes. Before the replacement of all the above mentioned parts, the car ran and drove fine, it just leaked a little water from the back of the left head. Can anyone tell me where the sensors that would set this code are located, and any other thoughts of what we may have screwed up. I think we are very close, as it does run smoothly, it's got to be something simple we forgot to hook up or hooked up wrong. thanks Brian

 

[frank moran]

the coolent temp sensor is on the bridge between the heads under the intake manifold, it also has the sender for your temp guage on it. Possibly you had the rad out and did not connect the fan switchs on the left tank or the electric pump in the same area?????

 

[ventport]

You nailed it, it was the coolent sensor on the bridge. I found a loose plug and plugged it in and the car works great now. Thanks for saving me a lot of time & trouble finding out what was wrong. Brian