Possible Causes
WARNING: This page is about a different car, the 2002 Mazda B4000, 2002 Mazda B3000, and 2002 Mazda B2300. However, it is still accessible from the selected car via links, so may be relevant.
Engine must be at normal operating temperature to pass KOEO self-test and KOER self-test. Ambient temperature must be more than 50°F (10°C) to receive acceptable input from IAT sensor. IAT, ECT and CHT sensors are thermistor type (passive) sensors. PCM uses IAT input as a correction factor in calculation of fuel, spark and MAF. PCM also uses ECT and CHT sensors as inputs. On all sensors, resistance changes with temperature. Resistance decreases with temperature increase, and increases with temperature decrease. Possible causes are:
- Overheating condition (P1116).
- Damaged harness (P1112 or P1117).
- Improper harness connection (P0112, P0113, P0117, P0118, P1289 or P1290).
- Grounded circuit in harness (P0112 or P0117).
- Damaged PCM (P0112, P1112, P0113, P1116, P0117, P1117, P0118, P1288, P1289 or P1290).
- Damaged ECT sensor (P0117, P0118, P1116 or P1117).
- Damaged CHT sensor (P1285, P1288, P1289 or P1290).
- Damaged IAT sensor (P0112, P1112 or P1113).
- Basic engine concerns (P1285 or P1299).
- Engine cooling concerns (P1285 or P1299).
- Insufficient warm-up time (P0125).
- Low engine coolant level (P0125, P1116, P1117, P1285, P1288 or P1299).
- Poor thermostat operation (P1116).
- Leaky or stuck open thermostat (P0125).
- Damaged harness connector (P1112, P1116, P1117 or P1288).
- Open in ECT harness (P0118).
- Grounded circuit in CHT harness (P1289 or P1290).
- Open circuit in CHT harness (P1289 or P1290).
- Short to power (P0113 or P0118).
- Open in IAT harness (P0113).
- CHT sensor concerns (P1285).