P0128

DTC P0128: Range/Performance Problem in Thermostat

NOTE: If the DTCs listed below are stored at the same time as DTC P0128, troubleshoot those DTCs first, then recheck for P0128.

P0107, P0108, P1128, P1129: MAP Sensor
P1106, P1107, P1108: Barometric Pressure Circuit
P0401: EGR Flow Insufficient
P1491: EGR Valve Lift Insufficient
P1498: EGR Valve Lift Sensor High Voltage
P0116, P0117, P0118: Engine Coolant Temperature Circuit
P0112, P0113: Intake Air Temperature Circuit
P0335, P0336, P1359: Crankshaft Position Sensor
P0300, P1399: Random Misfire
P0301, P0302, P0303, P0304: Cylinder 1, 2, 3 or 4 Misfire detected.
P0505: Idle Control System Malfunction
P1519: Idle Air Control Valve

DTC P0128 can set occasionally when the hood is opened.

1. Check the engine coolant level.
Is the engine coolant level low?
NO-Go to step 2.
YES-Refill the engine coolant. If necessary, check the cooling system.
2. Turn the ignition switch ON (II).
3. Check the radiator fan.
Does the radiator fan keep running?
YES - Check the radiator fan circuit, radiator fan switch circuit, and the radiator fan switch.
If they are OK, substitute the PCM and recheck.
If the symptom/indication goes away, replace the original PCM.
NO - Test the thermostat.