P0128

DTC P0128: Cooling System Malfunction ('02-04 models)

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: Manifold Absolute Pressure (MAP) Sensor
P1106,P1107, P1108(P2227, P2228, P2229)* : Barometric Pressure (BARO) Sensor
P1259: VTEC System
P0116, P0117, P0118 (P0125)* : Engine Coolant Temperature (ECT) Sensor
P0112, P0113: Intake Air Temperature (IAT) Sensor
P0335, P0336: Crankshaft Position (CKP) Sensor
P0300: Random Misfire Detected
P0301, P0302, P0303, P0304: No. 1, No. 2, No. 3 or No. 4 : Cylinder Misfire Detected
P0505 (P0506, P0507) *: Idle Control System
P1519 (P0511)*: Idle Air Control (IAC) Valve
*: '04 model

DTC P0128 can occasionally set when the hood is opened while the engine is running.

1. Check the engine coolant level.

Is the engine coolant level low?

YES - Refill the engine coolant. If necessary, repair the cooling leakage.

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.

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 a known-good ECM and recheck. If the symptom/indicator goes away, replace the original ECM.

NO - Replace the thermostat.