What does it mean?
C1279 is a Chassis (ABS, traction control, steering) fault code. It indicates: Acceleration Sensor Output Voltage Malfunction (Test Mode DTC) .
Symptoms
- Code appears mainly when the system is put into test mode with a scan tool
- ABS and stability lamps may illuminate during or after the test
- Stability and traction functions inhibited
- G sensor value offset from zero with the vehicle level and stationary
- ABS behaves unevenly on split-friction surfaces
Likely causes
- Acceleration (G) sensor output voltage outside the expected window while the system test routine was running
- Fault in the sensor supply or ground so the output sits at the wrong level
- Corroded, loose or wet sensor connector
- Sensor loose on its bracket or mounted at an angle, giving a permanent offset
- Internal sensor failure or drift with age
- Test carried out with the vehicle moving, on a slope or with the engine off, so the conditions were not met
- Control module input circuit fault
How to fix it
- Repeat the routine exactly as specified, with the vehicle stationary on level ground and the engine running
- Read the sensor output voltage in live data and compare it with the specified rest value
- Measure the sensor supply and ground at the connector with the ignition on
- Inspect the connector for corrosion and check the bracket bolts and sensor orientation
- Disconnect the sensor and test the circuit for open, short to ground and short to voltage
- Carry out the sensor zero point calibration and repeat the test
- Replace the acceleration sensor if the output stays outside the window with good supplies and wiring