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C3991 Engine Trouble Code

Meaning of C3991 engine trouble code is a kind of chassis trouble code and 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.

C3991 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 C3991 code is occuring now you should check C3991 repair processes.
Now don't ask yourself; What should you do with C3991 code ?
The solution is here :

C3991 Possible Solution:

C3991 Engine

Power Steering Pressure (PSP) Switch Malfunction In Key On, Engine Off Self-Test, this DTC indicates the PSP input to the PCM is high. In Key On, Engine Running Self-Test, this DTC indicates that the PSP input did not change state. Steering wheel must be turned during Key On, Engine Running Self-Test PSP switch/shorting bar damaged SIG RTN circuit open PSP circuit open or shorted to SIGRTN PCM damaged.

C3991 Code Meaning :

C 3 9 9 1
OBD-II Diagnostic Chassis (C) Trouble Code For Engine Ignition System Or Misfire Injector Circuit Malfunction - Cylinders Crankshaft Position Sensor A Circuit Malfunction Crankshaft Position Sensor A Circuit Low Input

The poor running symptoms are consistent with a MAP sensor malfunction. In addition, in some cases, a bad MAP sensor will not throw a code. Again, the ELD code likely represents a separate wiring issue.

C3991 OBD-II Diagnostic Chassis (C) Trouble Code Description

C3991 engine trouble code is about Crankshaft Position Sensor A Circuit Low Input.

Main reason For C3991 Code

The reason of C3991 OBD-II Engine Trouble Code is Injector Circuit Malfunction - Cylinders.

C3991 code on vehicles with electronically controlled automatic transmissions, the 3-4 shift solenoid is responsible for actuating the hydraulic circuits to activate clutches or bands that change gears inside the automatic transmission.