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U3999 Engine Trouble Code

Meaning of U3999 engine trouble code is a kind of network trouble code and when the check engine light comes U3999 code on the first you should check is the gas cap. Pull over, retighten it, and take a look at the cap to see if it has any cracks in it. Continue driving and see if the check engine light turns off. Alternately, you can purchase a gas cap for about $3 at an auto parts store. All you need to do is take the old one off and screw on the new one. If you've already made it to the store, you might as well just replace it. While not car-threatening, it's good to take care of this right away to improve gas mileage.

U3999 Fault Symptoms :

Check engine light comes on
Engine stalling or misfiring
Engine performance issues
Car not starting

If one of these reasons for U3999 code is occuring now you should check U3999 repair processes.
Now don't ask yourself; What should you do with U3999 code ?
The solution is here :

U3999 Possible Solution:

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.

U3999 Code Meaning :

U	3	9	9	9
OBD-II Diagnostic Network (U) Trouble Code For Engine	Ignition System Or Misfire	Injector Circuit Malfunction - Cylinders	Crankshaft Position Sensor A Circuit Malfunction	Reverse Input Circuit

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.

U3999 OBD-II Diagnostic Network (U) Trouble Code Description

U3999 engine trouble code is about Reverse Input Circuit.

Main reason For U3999 Code

The reason of U3999 OBD-II Engine Trouble Code is Injector Circuit Malfunction - Cylinders.

U3999 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.

	Example: 0140