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 (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

P0500: Vehicle speed sensor (VSS)

P0335, P0336 (P0339): Crankshaft position (CKP) sensor

P0300: Random misfire

P0301, P0302, P0303, P0304: No. 1, No. 2, No. 3 or No. 4 cylinder misfire detected

P0505 (P0506, P0507): Idle control system malfunction

P1519 (P0511): Idle air control (IAC) valve

* : '04 model

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

Check the engine coolant level.
Is the engine coolant level low?
1. YES - Refill the engine coolant. If necessary, repair the coolant leak.
2. NO - Go to step 2.
Turn the ignition switch ON (II), and make sure the A/C is off.
Check the radiator fan.
Does the radiator fan run continuously?
1. YES -Check the radiator fan circuit (see TROUBLE SHOOTING ), the radiator fan switch circuit open (see TROUBLE SHOOTING ), the radiator fan switch circuit short (see TROUBLE SHOOTING ), and the radiator fan switch (see COOLING FAN SWITCH ). Also, check for loose terminals in the ECT and IAT circuits. If the circuits, the switch, and the connections are OK, update the ECM/PCM if it does not have the latest software, or substitute a known-good ECM/PCM, then recheck (see ECM/PCM UPDATING AND SUBSTITUTION FOR TESTING ). If the symptom/indication goes away with a known-good ECM/PCM, replace the original ECM/PCM.
2. NO -Replace the thermostat (see THERMOSTAT REPLACEMENT ).