C1040 Diagnostic Trouble Code

C1040 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 C1040 diagnostic trouble code may include:

Poor fuel economy
Possible spark knock (detonation / pre-ignition)
Misfire
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
A plugged converter will cause of host of driveability problems as well as set this code. A severely plugged converter will result in the inability to increase rpm when under load. Look for a code such as P0421 -- catalytic converter efficiency below threshold if the converter indicating a faulty converter.

Repair Processes :

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 C1040 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 C1040.

Fortunately, C1040 is a fairly common OBD code, meaning that it applies to all makes and models of vehicles made after 1996.

C1040 Trouble Code For Specific Cars

C1040 Chevrolet Beretta Driver Mirror Power Driver Circuit Short Ground
C1040 Jaguar Xj Seat Driver Front Up Circuit Short To Battery
C1040 Tvr S Power Door Unlock Circuit Short To Battery
C1040 Monteverdi 400 Battery Power Relay Circuit Open
C1040 Daihatsu U4 GPS Antenna Open Circuit
C1040 Pininfarina Hit ESO - Engine Shut Off Solenoid Fault
C1040 Daihatsu Mira Generator Lamp "L" Control Circuit Malfunction