So, I had 2 CEL codes pop up. p1025 and p1155. i replaced the sensor for the p1155, Bank 2 sensor #1 already, had it cleared and its still showing the code. Anyone have any experience/ideas/suggestions on what can be done to eliminate this code or why it comes back. Also if anyone knows anything about code p1025, that would be helpful as well. coolant temp sensor, im gonna have to replace that sensor, and flush out of my coolant system see if that works, any other information at all would be most helpful. I do not wanna keep throwing out money for this check engine light to have the problem keep coming back. Thank you ALL.

 

P1155 is for the sensor heater current. When you replaced the sensor, did you use OEM or generic? Do you still have the old sensor? If so I would suggest measuring the resistance of the heater, and then comparing it to the new sensor. It should be just a few ohms (don't remember off the top of my head exactly how many).
The next thing to do is to check the wiring, according to the description of the code that I have, it could be either too little current, or too much. Each sensor has a heater which is connected to a switched +12volt source. There is a relay, and fuse in this circuit (but the relay powers all 4 sensors, so if you have only one code, the relay is probably good).

The other side of the sensor heater goes to the ecm. The ecm supplies the grd, and also measures the current in the circuit. So when this code is generated, it generally means 1 of 3 things.
1) the heater inside the sensor has opened up ( or many people say that some of the generic sensors can cause this, I have not experienced this, so I will not comment further on this).
2) there is a open in the circuit, either can be the supply or grd side
3) the ecm is bad.

 

Since it is bank 2 sensor one (the easy one to get to), I would suggest starting with backprobing the connector. You will need a DVM and a pin (as in a sewing needle or pin, borrow this from the wife or girlfriend). The idea is to slide the pin into the backside of the electrical connector (the side the wires go into). The pin is small enough to slide in, strong enough not to bend, and metal, so that it conducts current. You want to measure the voltages while the circuit is still intact. This is because the impedance of the meter will mask many issues with poor connections, (too complicated to explain the whole theory of impedance in this type of forum).

So with then engine power on, one side of the heater should read app 12v, the other side should read app 1 volt or lower. At this point, chances are that one is missing. Check both sides of the connector, so that you have 4 readings, this will verfiy the integrity of the connector. From the 4 readings that you get, you will be able to determine which direction to continue checking.

As far as the p1025 code, what year is your car? I looked up a 2000, but did not see that code. From your post, you indicate that it is the water temp sensor. I do not know if you are aware of this, but there is more than one water temp sensor, one is for the dash water temp gauge. The ECM uses it's own sensor.

 

Thanks George for all your insight, and very informative advice. It turns out the light shut off. i had driven it for about 50 miles and then see if it had cleared, it did not, however on my next trip, the codes cleared and the light went off. Problem solved. thank you for all your help