Got codes from auto zone po128 &po506
P0128 - Coolant Thermostat (Coolant Temperature Below Thermostat Regulating Temperature)
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:
Low engine coolant level
Leaking or stuck open thermostat
Faulty cooling fan (running too much)
Faulty coolant temperature (ECT) sensor
Faulty intake air temperature (IAT) sensor
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:
Verify coolant strength & level
Verify proper cooling fan operation (check if it's running more than it should). Replace if necessary.
Verify proper engine coolant temperature (ECT) sensor operation, replace if necessary.
Verify proper intake air temperature (IAT) sensor operation, replace if necessary.
If the above items check out good, replace the thermostat
If Nissan vehicle, check for Technical Service Bulletins (TSBs), as the ECM may need to be reprogrammed to correct the P0128 code
P0506 - Idle Air Control (IAC) System RPM Lower Than Expected
This P0506 code is one that's sometimes triggered on vehicles that have electronic throttle control. That is, they don't have a regular throttle cable from the accelerator pedal to the engine. They rely on sensors and electronics to control the throttle. In this case, the P0506 DTC (diagnostic trouble code) is triggered when the PCM (powertrain control module) detects an engine idle speed that is lower than the desired (pre-programmed) RPM.
Potential Symptoms: Most likely the only thing you'll notice is the idle speed is lower than normal so it will likely be rougher. There are potentially other symptoms as well. Of course, when trouble codes are set, the MIL (malfunction indicator lamp, a.k.a. the check engine light) illuminates.
Causes: A P0506 DTC trouble code may be caused by one or more of the following:
A vacuum leak
An air restriction in the intake air path or exhuast
A faulty positive crankcase ventilation (PCV) valve
Damaged/failed/dirty throttle body
Internal engine problem
Possible Solutions: This DTC is more of an informational code, so if there are any other codes set, diagnose them first. If there are no other codes, inspect for vacuum leaks, restrictions, and damage. If there are no symptoms other than the DTC itself, just clear the code and see whether it returns.
Check it, and keep us updated.
Apr 20, 2011 |
2004 Ford F150