What does it mean?
P1813 is a Powertrain (engine, transmission, fuel system) fault code. It indicates: Output Speed Sensor Circuit Malfunction Lower Threshold .
Symptoms
- Check engine lamp on, often with ABS, traction or stability warnings at the same time
- Speedometer reads zero or lags well behind actual road speed
- Transmission will not upshift normally and revs high in a low gear
- Torque converter clutch never applies, so fuel consumption rises noticeably
- Cruise control inoperative and the vehicle drops into limp mode
Likely causes
- Open circuit or high resistance in the signal or ground wire between the sensor and the module
- Signal wire shorted to ground through a chafed section against the transmission case or a bracket
- Connector filled with water, road salt or transmission fluid, corroding the terminals
- Sensor loose in its bore or shimmed incorrectly, leaving too wide an air gap
- Broken, rusted or oil-packed teeth on the output shaft reluctor ring
- Internally open sensor that stops working once it warms up
- Module input circuit damaged by an earlier short to ground
How to fix it
- Read the stored codes and the freeze frame; wheel speed codes appearing together point to a shared circuit or ground
- Unplug the sensor and inspect the connector for corrosion, moisture, fluid and spread terminals
- Measure sensor resistance or output against specification, then check both signal and ground wires for continuity and shorts
- Watch the output speed parameter on a scan tool while the vehicle is driven or safely rotated on a lift
- Remove the sensor and check the tip, the air gap and the condition of the reluctor teeth
- Repair the wiring or replace the sensor as the results demand, then verify the speed value tracks actual road speed
- If the value stays dead with good wiring and a good sensor, test the module supply, ground and input circuit