CEL on and issues

[smetzger]

Bought an '02 Protege, CEL came on during the drive home. Wahooo...

Code was a P0421 - replaced lower O2 sensor and cleared codes.

Got another CEL a bit later.. P0300. Spark plugs had oil in them, replaced valve cover gasket, plugs and wires. Cleared code.
P0300 came back. Replaced one coil pack. Cleared codes.

Got another CEL. P0171 System too lean (Bank 1).
Cleaned MAF. Did NOT clear codes.
CEL went off after some driving, but when I scan I still have a P0171 also the CAT, O2, and EGR are non-ready.

So, why would I not have a CEL but still have a code? Assuming everything is Ok, will he code eventually go away?

Thanks

[vw.fe2o3]

Try checking all the vac hoses and the large air intake hose. Take them off one at a time, roll them around and look for cracks where it's drying out and letting air in, especially the intake.
How many miles are on it?

[smetzger]

Try checking all the vac hoses and the large air intake hose. Take them off one at a time, roll them around and look for cracks where it's drying out and letting air in, especially the intake.
How many miles are on it?

I did replace the intake hose between the MAF and throttle body (previous owner had duct taped it up).
It has 155k miles.

I was thinking of seafoaming it. Any advice on the best place to suck it in and how to do it?

[smetzger]

Ok all fixed.

Here are the codes I was getting and the fixes...

P0421
- replace 2nd/lower O2 sensor

P0300
- oil in spark plugs - replaced valve cover gasket, spark plugs and cables
- coil pack bad - replaced

P0171
- vacuum leak on the PCV valve - put a hose clamp on it
- replaced first/pre-cat/top O2 sensor

P0140 - Pending only
- replaced first/pre-cat/top O2 sensor

One thing I did notice is that the CAT/O2 sensor would not be tested even after several drive cycles and 200 miles of day-to-day driving. But, as soon as I replace that top O2 sensor they were tested in one drive cycle. So, if your trouble shooting something and you have replace something and cleared the codes but its not going to tested/ready after a couple of drive cycles then your probably have not fixed the problem.