What does it mean?
P1792 is a Powertrain (engine, transmission, fuel system) fault code. It indicates: A/T Engine Coolant Temperature Sensor Circuit Malfunction .
Symptoms
- MIL (check engine lamp) is on and the coolant gauge may read incorrectly or not move
- Torque converter lockup is inhibited because the module thinks the engine is still cold
- Late, harsh shifts that never change as the vehicle warms up
- Cooling fans run constantly, or never run at all
- Fuel consumption climbs and the engine may run rich when cold
- Transmission may enter limp mode
Likely causes
- Coolant temperature sensor drifted, open or shorted internally
- Corroded or loose sensor connector, a common issue in a hot, damp underhood location
- Open, shorted or high-resistance signal or ground wire between the sensor and the modules
- Low coolant level or an air pocket around the sensor, so it never reads real coolant temperature
- The temperature message not reaching the transmission module because of a data bus fault
- Wrong sensor fitted after a repair, with a different resistance curve
- Control module input circuit fault
How to fix it
- After a cold soak, compare the coolant temperature reading with ambient temperature; they should be close
- Watch the value rise smoothly and continuously during warm-up, with no jumps or flat spots
- Measure the sensor resistance and compare it against the temperature and resistance table
- Back-probe the signal and ground at the sensor connector, and check the reference with the ignition on
- Check the coolant level and bleed any air from the system before condemning the sensor
- Verify the temperature value reaches the transmission module over the bus, then replace the sensor and confirm the reading