Toyota Camry, Error Code P0125

by Craig
(Cleveland, Ohio)

I have a 2000 Camry with a brand new water pump, timing belt and 2 coolant temperature sensors. The sensors were replaced because I got a fault code PO125. But, I still get that code. Is it most likely the thermostat? The car has only 66,000 miles, but the thermostat has never been replaced.



Steve Says,

Hi, Craig. Thanks for asking me your auto repair question.


The code you have (p0125) means that your car will not go into closed loop (which means that your computer gets its fuel mixture readings from your cars sensors instead of what is stored in its memory). Here are some ideas.


The first thing you should check is your coolant level. Make sure that your radiator is full and our reservoir is up to the full line as well. A low coolant level can easily cause this type of problem as well.


The next thing I would do is replace your cooling system thermostat. Quite often this will fix this type of code. The thermostat helps regulate the coolant temperature and helps to keep your car not only from overheating, but also from running too cold. On old cars the thermostat didn't matter as much as it does in today's newer cars. Car manufacturers are making engines to run at very specific temperatures and the thermostat helps them to run at that temperature.


If neither of these things fixes this problem then you can try one other thing. For some reason this code does not always mean what it should. Toyota sometimes uses code p0125 to refer to an oxygen sensor problem. I have no idea why this is the case, but it is. Basically this just means that if your cooling system has no problems and it is working as it should then maybe check out your o2 sensors and their wiring. It could easily be a problem of wires rubbing through and grounding out or it could mean that one of your oxygen sensors is bad. You can check the circuit by finding the o2 sensor in your exhaust system then following the wires and inspecting them to make sure they are in good condition.


OBD 2 Code p0125 should be an easy fix and easy diagnosis, but since this code sometimes means something other that what it should it makes it much more difficult to figure out.


I hope this has helped.