C3491 Diagnostic Trouble Code

C3491 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 C3491 diagnostic trouble code may include:

Poor acceleration
Cherry red hot catalytic converter
Possible spark knock (detonation / pre-ignition)
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
A large air leak at or near the number one oxygen sensor would also cause a lean mixture.

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. Now, clear the codes and test-drive the vehicle to see if the code is reset.

Process Tips

Diagnostic trouble code C3491 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 C3491.

Fortunately, C3491 is a fairly common OBD code, meaning that it applies to all makes and models of vehicles made after 1996.

C3491 Trouble Code For Specific Cars

C3491 Nissan Sentra Cruise Control Command Switch Assembly Circuit Failure
C3491 Amc Gremlin Air Suspension Front Inflator Solenoid Output Circuit Failure
C3491 Hillman Hawk Passenger's Seatback Autoglide Rearward Switch Circuit Short to Ground
C3491 Maserati 450 Transmission Fluid Pressure Sensor/Switch A Circuit High
C3491 Autobianchi Bianchina Aux Heater Coolant Sensor Circuit Short to Ground
C3491 Honda Saber Reference Voltage Out of Range (+5 v)
C3491 Shelby Super Cars Aero Intake Air Temperature Circuit Intermittent