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? YES - Refill the engine coolant. If necessary, repair the coolant leak. 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? YES -Check the radiator fan circuit (see «TROUBLE SHOOTING»(ref-165372-S13302424852004082500000) ), the radiator fan switch circuit open (see «TROUBLE SHOOTING»(ref-165372-S13302424852004082500000) ), the radiator fan switch circuit short (see «TROUBLE SHOOTING»(ref-165372-S13302424852004082500000) ), and the radiator fan switch (see «COOLING FAN SWITCH»(ref-165372-S22627609792004082500000) ). 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»(ref-171385-S32387647222005020300000) ). If the symptom/indication goes away with a known-good ECM/PCM, replace the original ECM/PCM. NO -Replace the thermostat (see «THERMOSTAT REPLACEMENT»(ref-171732-S14382795782005021000000) ).