What does it mean?
P1492 is a Powertrain (engine, transmission, fuel system) fault code. It indicates: Battery Temperature Sensor Circuit High Input .
Symptoms
- MIL on
- Charging voltage too high or too low, because the module cannot temperature compensate
- Battery gassing, a sulphur smell or noticeably short battery life
- Headlights unusually bright or dim at idle in some cases
- Scan tool shows an implausible battery temperature at the low end of the scale
- Repeat battery or charging system complaints
Likely causes
- Open in the battery temperature sensor signal or ground circuit
- Sensor with an internally open thermistor element
- Corroded connector at the sensor, which usually sits under or beside the battery tray
- Battery acid vapour damage to the harness and terminals
- Signal wire shorted to the reference voltage line
- Sensor housing cracked or dislodged during a previous battery replacement
- Module input circuit fault
How to fix it
- Compare the sensor reading on the scan tool with actual underhood temperature after an overnight cold soak
- Inspect the sensor and its connector for acid damage and green corroded terminals
- Test the signal and ground sides of the circuit for an open
- Measure the sensor resistance and compare it with the temperature and resistance chart
- Check charging system voltage under no load and with heavy electrical load
- Repair the corroded wiring, or replace the sensor if it is out of range
- Clear the code and confirm a plausible temperature reading and correct charging voltage