96 - CEL & Code 174

[Stewart in CO]

Our 96 has just over 100,000 miles on it. The check engine light just came on and I got a code of 174 - lean engine bank #2. Any ideas? Thanks!

[wiswind]

The MOST likely cause is a vaccum leak.
It is very unlikely a bad oxygen sensor, in spite of what the clerk at the auto part store may tell you.

Bank #2 is the front bank of cylinders, 4, 5, 6.
Bank #1 is the back bank of cylinders, 1, 2, 3.
Easy way to remember.....bank #1 has Cylinder #1
It is possible that this could be caused by somewhat dirty fuel injectors....but eliminate the vaccum leak possibility first.
It could be a leak that impacts both banks, but the PCM tripped for 1 first.....due to slight differences in oxygen sensors, etc.

One place to check is the elbow in the PCV line......located on top of the upper intake manifold, right next to the throttle body.
Mine developed a crack on the inside of the bend.
Follow that line back, and verify that everything is connected, not melted, etc.

Also, verify that the crankcase breather tube, goes from the passenger side of the front valve cover and into the air intake flex pipe that connects to the throttle body. The Breather tube connects to the back side of that flex pipe.

There are a LOT of vaccum connections on the back side of the upper intake manifold. Any one of those could lead to a vaccum leak.
The ones I mentioned are easy to check, and also easy to have been bumped loose.

If you cannot find a vaccum leak, it is possible that your MAF (Mass Air Flow sensor) needs cleaning with a non-residue ELECTRONIC cleaner.
I have pictures of where you want to spray the cleaner to clean the sensors.
The sensors are located inside the hollow plastic cross bar behind the screen which faces the air filter.