The best thing to do is, remove and clean all the sensors and connectors I have listed below.A code P0125 may mean that one or more of the following has happened:
- Insufficient warm up time
- Low engine coolant level
- Leaking or stuck open thermostat
- Faulty coolant temperature sensor
Possible Solutions
The simplest thing to do is to reset the code and see if it comes back.
If the code comes back, the problem is likely going to be the result of the
above causes (faulty thermostat, faulty
ECT sensor, or a low coolant level).
Other ECT sensor and circuit related DTCsA code
P0171 may mean that one or more of the following
has happened:
- The MAF (Mass Air Flow) Sensor is dirty or faulty
Note: The use of "oiled"
air filters may cause the MAF to become dirty if the filter is over-oiled.
There is also an issue with some vehicles where the MAF sensors leak the silicone
potting material used to protect the circuitry.
- There could be a vacuum leak downstream of the MAF sensor
- Possible cracked vacuum or PCV line/connection
- Faulty or stuck open PCV valve
- Failed or faulty oxygen sensor (bank 1, sensor 1)
- Sticking/plugged or failed fuel injector
- Low fuel pressure (possible plugged/dirty fuel filter!)
- Exhaust leak between engine and first oxygen sensor
Possible Solutions
A lot of times, cleaning the MAF sensor and finding/fixing vacuum
leaks fix the problem. If you're on a tight budget, start there, but
that may not be the fix for certain. So, possible solutions include:
- Clean the MAF sensor.
Consult your service manual for it's location if you need help. I find it's
best to take it off and spray it with electronics cleaner or brake cleaner.
Make sure you are careful not to damage the MAF sensor, and make sure it's
dry before reinstalling
- Inspect all vacuum and PCV hoses, replace/repair as required
- Inspect all hoses and connections in the air intake system
- Inspect and/or test the intake manifold gaskets for leakage
- Check for a dirty fuel filter and proper fuel pressure
- Ideally you'll want to monitor short and long term fuel trims using an advanced scan tool