C0977 Diagnostic Trouble Code

C0977 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 C0977 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 :

Pack the connector cavity with dielectric silicone compound (same stuff they use for light bulb sockets and spark plug wires) and reassemble. 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. 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.

Process Tips

Diagnostic trouble code C0977 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 C0977.

Fortunately, C0977 is a fairly common OBD code, meaning that it applies to all makes and models of vehicles made after 1996.

C0977 Trouble Code For Specific Cars

C0977 Connaught L2 Fuel Restriction Condition
C0977 Alfa Romeo Concept Accessory Delay Relay Coil Circuit Short To Ground
C0977 Daihatsu Gran Gear Shift Reverse Actuator Circuit / Open [rearward motion, even gears, 2,4,6]
C0977 Bmw 3 Can Link ECM/INSTM Circuit / Network Malfunction
C0977 Delahaye Gfa Hydraulic Pressure Sensor Range/Performance
C0977 Rover 600 Ignition Coil C Primary/Secondary Circuit Malfunction
C0977 Nissan Nv200 Control Module VSS Output "B" Malfunction