P0128

DTC P0128: Cooling System Malfunction

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: Barometric Pressure (BARO) Sensor
P1259: VTEC System
P0116, P0117, P0118: Engine Coolant Temperature (ECT) Sensor
P0112, P0113: Intake Air Temperature (IAT) Sensor
P0335, P0336: Crankshaft Position (CKP) Sensor
P0300: Random Misfire
P0301, P0302, P0303, P0304: No.1, No.2, No.3 or No.4 Cylinder Misfire
P0505: Idle control System
P1519: Idle Air Control (IAC) Valve

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.