Bank 1 too lean?

TIGGA1633

MEMBER
VOLKSWAGEN

I have a 2001 Jetta 2.0 about 89,000 miles. This car has had numerous problems since I got it. With in 2 weeks one of the fans went out, then the oil cooler broke. After 4 flushes of the coolant system about a month apart, I still have traces of oil in my coolant. Most recently, I had about 1/4 tank of gas, stopped at a Chevron to fill up. As soon as I got back in the car, the check engine light was on. I have ran the code at home, and it comes up p0171, saying "bank 1 too lean" I have been running fuel injector cleaner in with each full tank the last 2 weeks or so. ( I believe it is lucas's brand not sure of the spelling) that hasn't helped. I pulled out both O2 sensors, neither looked really bad. I have also cleaned out the throttle body, the air filter, and MAF sensor. I have pulled apart other little things but made no progress. I have turned off the light a few times. It will stay off for a few hours (driving, starting and stopping the car) then go back on. Any other options I can try other then pull out the fuel injectors and have them cleaned? Thanks.
Also. When I start the car, the coolant light always comes on. Stays on until the car warms up, then goes off. When inspecting the overflow tank, I found small clumps of oil on the prongs on the inside of the tank where the plug is. Could that be the problem?

1 Reply

BRUCE HUNT

MECHANIC
3,754 POSTS

First, I would highly caution you against running too much fuel injector cleaner through the system. I might do some good but can eventually do more harm than good. The oil is not really the cause but more of a symptom. For what I am not sure, but it could be head and valve seal related.

It is very unusual to look at an O2 sensor and see if it looks good or bad. They can be tested. You could have a timing issue that is causing the lean problem.

Either way you have some issues to address. The most critical right now is the oil in the coolant problem. Four flushes should have gotten out the oil from the system, regardless, unless the previous owner put oil in the coolant, it appears that the oil is still finding its way in to the coolant. It is time to start digging deeper.