P0128

DTC P0128: Range/Performance Problem in Thermostat

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

P0107, P0108, P1129: MAP Sensor
P1106, P1107, P1108: Barometric Pressure Circuit
P1259: VTEC system
P0401: EGR Flow Insufficient
P1491: EGR Valve Position Insufficient
P1498: EGR Valve Position Sensor High Voltage
P0116, P0117, P0118: Engine Coolant Temperature Circuit
P0112, P0113: Intake Air Temperature Circuit
P0335, P0336, P1359: Crankshaft Position Sensor
P0300: Random Misfire
P0301, P0302, P0303, P0304, P0305, P0306: Cylinder 1,2,3,4,5 or 6 Misfire Detected
P0505 :Idle Control System Malfunction
P1519: Idle Air Control Valve

DTC P0128 can occasionally set when the hood is opened.

1. Check the engine coolant level.

Is the engine coolant level low?

YES - Refill the engine coolant. If necessary, check the cooling system.

NO - Go to step 2.

2. Turn the ignition switch ON (II), and make sure the A/C is off.
3. Check the radiator fan.

Dose 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.