C129A Diagnostic Trouble Code

C129A is a kind of OBD-II Diagnostic C-Chassis Diagnostic Trouble Code.

It is considered generic because it applies to all makes and models of vehicles, although specific repair steps may be different depending on your car model.

Symptoms

Symptoms of a C129A diagnostic trouble code may include:

Faulty PCM
The light may stay on or light intermittently as the DPF regenerates. The engine will be sluggish on acceleration.
Poor acceleration
If the DPF is not cleared the ECU will revert to the "Limp Home Mode" until the situation is corrected

Possible Causes :

Fuel with a large percentage of sulfur will clog the DPF quickly
The Mass Airflow sensor will also cause this problem. Mass Airflow circuit malfunction.
A large air leak at or near the number one oxygen sensor would also cause a lean mixture.

Repair Processes :

Find out what kind of system you have and verify that voltage to the fuel level sensor is present at the fuel pump wiring harness. Replace the oxygen sensor that is downstream from the catalytic converter on the side of the engine that does not contain cylinder #1. Also, if a oxygen sensor code stating "heater circuit malfunction" the sensor has most probably failed. Now, clear the codes and test-drive the vehicle to see if the code is reset.

Process Tips

Diagnostic trouble code C129A is not difficult to diagnose and repair. Thus, it always pays to have a qualified technician to look after your vehicle should this error code arise.

Diagnosing this code requires the engine to be in good running shape, without unmetered air entering the engine. If other codes that relates to misfiring condition, lean running or air entering the engine is present, then you must first fix those error codes before C129A.

Fortunately, C129A is a fairly common OBD code, meaning that it applies to all makes and models of vehicles made after 1996.

C129A Trouble Code For Specific Cars

C129A Chrysler Kew Evaporative Emission Control System Pressure Sensor Intermittent
C129A Bucciali Tav Cylinder #1 High To Low Side Open
C129A Ginetta G21 Oil Temperature Sensor Circuit Failure
C129A Chevrolet Eight Driver's Door Unlock Relay Circuit Short to Battery
C129A Ferrari F2005 Intermediate Shaft Speed Sensor Circuit Intermittent
C129A Chevrolet Silverado 3 ELC System Closure Valve Flow Fault
C129A Volkswagen Voyage