C3129 Diagnostic Trouble Code

C3129 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 C3129 diagnostic trouble code may include:

Misfire
Misfire
The light may stay on or light intermittently as the DPF regenerates. The engine will be sluggish on acceleration.
The engine oil will exhibit dilution from the ECUs attempts to increase engine temperature. Some vehicles advance the fuel injection timing slightly after top center to afterburn a small amount of fuel to increase exhaust temperatures. Some of this fuel enters the crankcase. When the ECU determines the necessity to regenerate the DPF, the service life of the oil be shortened significantly

Possible Causes :

A large vacuum leak would cause a massive amount of un-metered air to enter the intake manifold resulting in an overly lean mixture.
Faulty IMRC actuator/sensor
An air leak forward of the DPF will change the sensor readings resulting in the code

Repair Processes :

If the engine displays a miss and there wasn't a code, determine which cylinder is misfiring. If the exhaust manifold is visible, spay or pour a small amount of water on each cylinder exhaust port. Water will evaporate immediately on good cylinders and slowly on the missing cylinder. If this can't be accomplished pull the plugs and check the condition. It should be pretty close to battery voltage (12 volts). If not, then this is the circuit that has the problem. 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.

Process Tips

Diagnostic trouble code C3129 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 C3129.

Fortunately, C3129 is a fairly common OBD code, meaning that it applies to all makes and models of vehicles made after 1996.

C3129 Trouble Code For Specific Cars

C3129 Austin A60 Autolamp Delay Increase Circuit Short To Ground
C3129 Toyota Corsa O2 Sensor Circuit No Activity Detected (Bank 2 Sensor 3)
C3129 De Dietrich De Dietrich HO2S Heater Resistance (Bank 1 Sensor 1)
C3129 Autobianchi Bianchina Aux Heater Coolant Sensor Circuit Short to Ground
C3129 Renault Trafic HO2S Heater Control Circuit High (Bank 1 Sensor 2)
C3129 Honda N360 RADIO PRESENT SWITCH Ckt Failure
C3129 Renault Trafic 3 HO2S Heater Control Circuit High (Bank 2 Sensor 1)