C1785 Diagnostic Trouble Code

C1785 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 C1785 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 :

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. Look for damage to the tank indicating impact that may have damaged the fuel pump or sender.

Process Tips

Diagnostic trouble code C1785 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 C1785.

Fortunately, C1785 is a fairly common OBD code, meaning that it applies to all makes and models of vehicles made after 1996.

C1785 Trouble Code For Specific Cars

C1785 Pontiac Solstice Flash To Pass Switch Circuit Short To Battery
C1785 Ginetta G15 Oil Level Switch Circuit Short To Ground
C1785 Overland 42 Double Locking Door Motor Frozen
C1785 Hyundai Equus SCP (J1850) Invalid or Missing Data for Antenna
C1785 Glas 1500 Overdrive switch circuit short to Vbatt
C1785 Trabant P70 Passenger Sid, Side mount Airbag Low capacitance on Squib
C1785 Mercedes S 600 Air Bag Crash Sensor #1 Feed/Return Circuit Failure