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 *1 , P1107 *1 , P1108 *1 (P2227, P2228, P2229) **2 Barometric Pressure (BARO) sensor
P1259 *1 (P2246, P2247) **2 : VTEC system
P0116, P0117, P0118 (P0125) **2 : Engine Coolant Temperature (ECT) sensor
P0112, P0113: Intake Air Temperature (IAT) sensor
P0500: Vehicle Speed Sensor (VSS)
P0335, P0336 *1 (P0339) **2 : 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 *1 (P0506, P0507) **2 : Idle control system malfunction
P1519 *1 (P0511) **2 : Idle Air Control (IAC) valve
*1:'02-03 models
**2:'04-05 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, the radiator fan switch circuit open, the radiator fan switch circuit short, and the radiator fan switch. See «ELECTRIC COOLING FANS (EXCEPT HYBRID)»(ref-165227) . If they are OK, update the ECM if it does not have the latest software, or substitute a known-good ECM, then recheck (see «ECM UPDATING AND SUBSTITUTION FOR TESTING»(ref-171994-S19233909092005021700000) ). If the symptom/indication goes away with a known-good ECM, replace the original ECM. NO: Replace the thermostat (see «THERMOSTAT REPLACEMENT»(ref-171331-S37128263272005020200000) ).