Your OBD-II Trouble Codes Repair Site

P0128 OBD-II Trouble Code

Technical Description

Coolant Thermostat (Coolant Temperature Below Thermostat Regulating Temperature)

What does that mean?

This means that the engine's PCM detected that the engine has not reached the required temperature level within a specified amount of time after starting the engine. The intent of the P0128 code is to indicate a faulty thermostat. Similar codes: P0125

In determining the engine did not reach a "normal" temperature, it takes into account the length of time the vehicle has been running, the intake air temperature (IAT) sensor reading, the engine coolant temperature (ECT) sensor reading, and the speed of the vehicle.

Symptoms

You will likely not notice any drivability problems other than the MIL illumination.

Causes

A code P0128 may mean that one or more of the following has happened:

Possible Solutions

Past experience indicates that the most likely solution is to replace the thermostat. However here are some suggestions on troubleshooting and repairing a P0128 OBD-II code:

Other ECT sensor and circuit related DTCs: P0115, P0116, P0117, P0118, P0119, P0125

Looking for a code reader or auto parts? Shop Amazon.com now

Related P0128 DTC Discussions

Need more help with a p0128 code?

If you still need help regarding the P0128 trouble code, please post your question in our FREE car repair forums.

NOTE: This information is presented for information purposes only. It is not intended as repair advice and we are not responsible for any actions you take on any vehicle. All information on this site is copyright protected. If you want to share this article or information with others, please link to this page, don't copy and paste it elsewhere.