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B3991 Engine Trouble Code

Meaning of B3991 engine trouble code is a kind of body 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.

B3991 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 B3991 code is occuring now you should check B3991 repair processes.
Now don't ask yourself; What should you do with B3991 code ?
The solution is here :

B3991 Possible Solution:

B3991 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.

B3991 Code Meaning :

B 3 9 9 1
OBD-II Diagnostic Body (B) 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.

B3991 OBD-II Diagnostic Body (B) Trouble Code Description

B3991 engine trouble code is about Crankshaft Position Sensor A Circuit Low Input.

Main reason For B3991 Code

The reason of B3991 OBD-II Engine Trouble Code is Injector Circuit Malfunction - Cylinders.

B3991 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.