U3997 Lexus Auto Trouble Code

U3997 Lexus OBD2 may also be triggered by faults earlier down the line. For example, a dirty MAF sensor might be causing the car to overcompensate in its fuel-trim adjustments. As a result, oxygen sensors are likely to report fuel mixture problems.

The computer notices the canister is empty when it detects a leaner condition (all the vapors are used up) and it resumes normal fuel delivery. Some car manufacturers then close the vent solenoid but leave the purge solenoid open. That creates a vacuum throughout the entire fuel storage system. Once the correct vacuum is reached, it closed the purge solenoid and waits to see if the vacuum holds.

U3997 Lexus 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.

U3997 Lexus Description For All Models :

U3997 Lexus Trouble Repair :

The U3997 Lexus check engine lamp is perhaps the most troubling of lights because it could mean so many different things, from you didn't screw the gas cap on tightly enough to look out for pistons flying through the hood and into the stratosphere. The easiest way to find out what this light is telling you is to hook your vehicle up to a scan tool. OBD 2 diagnostic tool looks a little like an oversized calculator and plugs into a communication port inside the car. After you instruct it to perform the scan, it speaks with your car's computers to find out exactly what's prompting the light to turn on.

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