C0842 Diagnostic Trouble Code

C0842 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 C0842 diagnostic trouble code may include:

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
Faulty or damaged wiring
Hesitation upon acceleration
The light may stay on or light intermittently as the DPF regenerates. The engine will be sluggish on acceleration.

Possible Causes :

An air leak forward of the DPF will change the sensor readings resulting in the code
Rusty exhaust systems, cracked exhaust manifolds or damaged or missing gaskets or donuts will cause air leaks.
Defective ECU strategies or components will prevent proper regeneration

Repair Processes :

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. 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. Look at the plug wires to make sure they are not burnt or laying on the exhaust.

Process Tips

Diagnostic trouble code C0842 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 C0842.

Fortunately, C0842 is a fairly common OBD code, meaning that it applies to all makes and models of vehicles made after 1996.

C0842 Trouble Code For Specific Cars

C0842 Citroen Evasion Fuel level Sensor Circuit Low Input
C0842 Mitsubishi Field Guard Autolamp Delay Decrease Circuit Short To Battery
C0842 Audi A1 Ambient Air Temperature Sensor Circuit Intermittent
C0842 Honda Acura Nsx Pressure Control Solenoid B Intermittent
C0842 Nissan R390 Crankshaft Position Sensor A Circuit Malfunction
C0842 Mercedes E 63 Accelerometer Front Circuit Short To Battery
C0842 Piontek Sport-tech Evaporative Emission (EVAP) System Flow During Non-Purge Oldsmobile Only