2003 Volkswagon Jetta GLS 1.8t. Codes P0171 and P0340 are coming up on my jetta. What needs to be done to get rid of the check engine light?
For p0171 this a lean code you need to check all the vacuum lines that connect to the engine this is the most common cause of this. If you cannot find any vacuum lines that are broken then the second most common problem would be a Mass Air Flow sensor.
The p0340 fault is usually seen after a timing belt replacement and the timing is off a tooth. Have you had the timing belt replaced recently. If not then your belt tensioner may have malfunctioned and caused slack in the belt, but 99 times out of 100 it is the timing belt being off of time.
Do you have any other questions?