Logo

U0991 Engine Code Repair

Meaning of U0991 engine trouble code is a kind of network trouble code and when your car's 'U0991 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.

U0991 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 U0991 code is occuring now you should check U0991 repair processes.
Now don't ask yourself; What should you do with U0991 code ?
The solution is here :

U0991 Possible Solution:

U0991 Engine

Air Conditioning Pressure Sensor (ACP) Insufficient Pressure Change Each time the A/C clutch engages, the PCM is looking for a pressure change in the refrigerant. If the change in pressure is outside of the calibration the DTC will set. A/C system mechanical failure Open ACP or VREF circuit A/C sensor damaged A/C system electrical failure A/C clutch always engaged Verify A/C system function, including refrigerant charge.

U0991 Code Meaning :

U
OBD-II Diagnostic Network (U) Trouble Code For Engine

0
Intake Valve Control Solenoid Circuit Low

9
Engine Oil Temperature Sensor Malfunction

9
Ignition/Distributor Engine Speed Input Circuit Malfunction

1
Shift Solenoid E Performance or Stuck Off

The oxygen (02) sensors on your car measure the oxygen in the exhaust to determine how rich or lean the ratio of fuel and air are in the cylinders. Optimizing this mixture means better fuel economy and fewer exhaust emissions.

U0991 OBD-II Diagnostic Network (U) Trouble Code Description

U0991 engine trouble code is about Shift Solenoid E Performance or Stuck Off.

Main reason For U0991 Code

The reason of U0991 OBD-II Engine Trouble Code is Engine Oil Temperature Sensor Malfunction.

U0991 DTC reports a sensor fault, replacement of the sensor is unlikely to resolve the underlying problem. The fault is most likely to be caused by the systems that the sensor is monitoring, but might even be caused by the wiring to the sensor itself.