C1138 Diagnostic Trouble Code

C1138 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 C1138 diagnostic trouble code may include:

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

Possible Causes :

Rarely - faulty Powertrain Control Module (PCM-programming required after replacement)
Rough running engine due to misfiring plugs. Many engines have misfire codes to indicate the cylinder effected, such as P0307 for number 7.
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. If all testing has passed so far yet you still have the same code, check your scan tool and see if it can open and close the IMRC valve. Look at the plug wires to make sure they are not burnt or laying on the exhaust.

Process Tips

Diagnostic trouble code C1138 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 C1138.

Fortunately, C1138 is a fairly common OBD code, meaning that it applies to all makes and models of vehicles made after 1996.

C1138 Trouble Code For Specific Cars

C1138 Volvo S80
C1138 Proton Preve Fuel Stepper Motor Malfunction
C1138 Suzuki Swift Mirror Driver Right Circuit Short To Battery
C1138 Standard Vanguard Lamp Keypad Output Short Circuit To Battery
C1138 Citroen Bijou Front Echo Sensor Circuit Failure
C1138 Napier 18 Camshaft Position Sensor Circuit Malfunction
C1138 Mercedes-benz V Class Air Suspension Gate Solenoid Output Circuit Short To Ground