C0129 Diagnostic Trouble Code

C0129 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 C0129 diagnostic trouble code may include:

Cherry red hot catalytic converter
Poor acceleration
The light may stay on or light intermittently as the DPF regenerates. The engine will be sluggish on acceleration.
Reduction in engine performance, especially at low RPM levels

Possible Causes :

A faulty oxygen sensor. This will set a code in itself, however, a faulty oxygen sensor does not automatically condemn the sensor. The code just means that the sensor signal was not within specifications. An air leak or any of the above will cause an erroneous signal. There is a multitude of O2 codes relating to O2 performance which gives a clue to the problematic area.
Some aftermarket accessories and performance modifications
An air leak forward of the DPF will change the sensor readings resulting in the code

Repair Processes :

With the valve disconnected, the red voltmeter lead should be attached to the IMRC valve power wire and the black voltmeter lead connected to ground. Check to make sure they are not burnt or corroded. If in doubt, get some Electrical Contact cleaner at any parts store if cleaning of the terminals is needed.

Process Tips

Diagnostic trouble code C0129 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 C0129.

Fortunately, C0129 is a fairly common OBD code, meaning that it applies to all makes and models of vehicles made after 1996.

C0129 Trouble Code For Specific Cars

C0129 Mg M-type Air Suspension Warning Lamp Circuit Open
C0129 Tvr 450 Power Door Lock Circuit Short To Ground
C0129 Bmw X5 Column Reach Feedback Potentiometer Circuit Short to Battery
C0129 Ford Tickford Mirror Switch Assembly Circuit Failure
C0129 Holden Rc Colorado Power To A/C Clutch Circuit Overcurrent
C0129 Glas 3000 PAD Warning Lamp Inoperative
C0129 Mercedes Cls 500 ABS Outlet Valve Coil RR Circuit Failure