C0739 Diagnostic Trouble Code

C0739 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 C0739 diagnostic trouble code may include:

Hesitation upon acceleration
Excessive exhaust leak
Rich or lean exhaust
Reduction in engine performance, especially at low RPM levels

Possible Causes :

A faulty oxygen sensor. This will set a code in itself, however, a faulty oxygen sensor does not automatically condemn the sensor. The code just means that the sensor signal was not within specifications. An air leak or any of the above will cause an erroneous signal. There is a multitude of O2 codes relating to O2 performance which gives a clue to the problematic area.
Some aftermarket accessories and performance modifications
Dirty air cleaner element Damaged DPF

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. 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 C0739 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 C0739.

Fortunately, C0739 is a fairly common OBD code, meaning that it applies to all makes and models of vehicles made after 1996.

C0739 Trouble Code For Specific Cars

C0739 Pininfarina Hit ESO - Engine Shut Off Solenoid Fault
C0739 Dodge Mirada Ignition Retard Request Circuit Fault
C0739 Citroen C-zero Fuel Level Output Circuit Malfunction
C0739 Lada 1600 Shift Solenoid A Control Circuit High
C0739 Sunbeam Alpine Manifold Absolute Pressure/Barometric Pressure Circuit Range/Performance Problem
C0739 Renault Grand Espace Glow Plug Circuit High Side, High Input
C0739 Pontiac Grand Prix Exhaust Valve Control Solenoid Circuit Range/Performance (Bank 1)