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U0391 Engine Trouble Code

Meaning of U0391 engine trouble code is a kind of network trouble code and when your car's 'U0391 Check Engine' light comes on, it's usually accompanied by a sinking feeling in the pit of your stomach. The light could mean a costly problem, like a bad catalytic converter, or it could be something minor, like a loose gas cap. But in many cases, it means at minimum that you'll be visiting the car dealer to locate the malfunction and get the light turned off.

U0391 Fault Symptoms :

  1. Check engine light comes on
  2. Engine stalling or misfiring
  3. Engine performance issues
  4. Car not starting
If one of these reasons for U0391 code is occuring now you should check U0391 repair processes.
Now don't ask yourself; What should you do with U0391 code ?
The solution is here :

U0391 Possible Solution:

U0391 Engine

The crankshaft sensor signals the fuel injection computer or the ignition control when the cylinders are firing. This causes the ignition coil to provide a spark and the injector to inject fuel into each cylinder at the right time.If either sensor isn't working correctly, the car will run rough and the engine will be less efficient. In later car models, the car's computer can usually keep the vehicle running, but the engine warning light on the dashboard goes on to warn the driver.

U0391 Code Meaning :

U 0 3 9 1
OBD-II Diagnostic Network (U) Trouble Code For Engine Intake Valve Control Solenoid Circuit Low Throttle/Pedal Position Sensor/Switch A Circuit Intermittent Crankshaft Position Sensor A Circuit Malfunction Crankshaft Position Sensor A Circuit Low Input

Is the fuel pump sometimes not priming when you turn the key to ON(II)? Start by measuring the fuel pressure and checking whether you have bright white-bluish spark at all four plugs. The mechanical timing is also something that you should check, as we mentioned above.

U0391 OBD-II Diagnostic Network (U) Trouble Code Description

U0391 engine trouble code is about Crankshaft Position Sensor A Circuit Low Input.

Main reason For U0391 Code

The reason of U0391 OBD-II Engine Trouble Code is Throttle/Pedal Position Sensor/Switch A Circuit Intermittent.

U0391 DTCs may also be triggered by faults earlier down the line. For example, a dirty MAF sensor might be causing the car to overcompensate in its fuel-trim adjustments. As a result, oxygen sensors are likely to report fuel mixture problems.