P0391 Engine Trouble Code
When you check engine light came on code P0391 the reason should be Engine Light ON (or Service Engine Soon Warning Light). However your vehicle's manufacturer may have a different definition for the P0391 OBD-II Diagnostic Powertrain (P) Trouble Code. So you should chech it on our car models.
Theoretically you can drive for a few weeks or even months with a broken MAF sensor. You will notice a decrease in gas mileage and over time the car will eventually start stalling a lot. At a shop, the replacement cost is between $200-$300 depending on the car, but that's usually the cost of parts because the labor is relatively simple.
P0391 Code Meaning :
|OBD-II Diagnostic Powertrain (P) Trouble Code For Engine||Intake Valve Control Solenoid Circuit Low||Fuel Rail Pressure Sensor Circuit Malfunction||Cylinder 4 Contribution/Balance Fault||Glow Plug/Heater Circuit 'A' Malfunction|
The catalytic converter has an oxygen sensor in front and behind it. When the vehicle is warm and running in closed loop mode, the upstream oxygen sensor waveform reading should fluctuate.
P0391 OBD-II Diagnostic Powertrain (P) Trouble Code DescriptionP0391 OBD-II Trouble Code The Camshaft Position Sensor is an electronic device used in an engine to record the rate at which the camshaft is spinning. This information is used by the Engine Control Module ( P0391 code.
Reason For P0391 CodeThe reason of P0391 OBD-II Engine Trouble Code is Fuel Rail Pressure Sensor Circuit Malfunction.
P0391 DTC specifically refers to the camshaft (cam) timing. In this case, if the cam timing is over-retarded, the engine light will be illluminated and the code will be set.