Hey all,

2004 Disco II 4.6 Bosch

Was getting some codes; namely,
P0441 evap emissions purge
P0150 02 bank 2 sensor 1
P0174 fuel too lean

Recently changed my o2 sensor and solved the last two.

Today, two weeks later, I took apart the hoses from the purge valve and cleaned the inside of the solenoid really well and let the rest evaporate before putting it back on.

Sure enough, the code did not reappear; however, the O2 codes started showing up again. It was like a direct exchange of codes.

Cleaned the gas cap threads and seal, everything looks okay.

Could this sequence of events be a sign of a catalytic converter going bad or a bad fuel pump/fuel filter?

Any tips would be very appreciated.

Thanks.

[edit]:
I have the secondary air installation, as well.

 

I’m not seeing how a failing Cat could cause that.

 

I’m trying to figure what might be setting these sensors off and attempting to piece together symptoms of a larger issue.

All I can reasonably deduce is that it may be some electrical issue.

 

A P0174 lean code often indicates a vacuum leak. It's more typically seen paired with P0171 for Bank 1.

Most lean codes are triggered by a vac leak affecting both banks, which is why P0171 and P0174 are often seen paired. A vac leak or leaks affecting Bank 2 only could be leaking fuel injector O-rings. Off the top of my head I can't think of anything else that would affect only one bank.

Smoke tests are often recommended to track down vac leaks, but I don't know how effective a smoke test is for identifying leaking fuel injector O-rings. Replacements should be inexpensive, but replacing them would be a drag, for me at least.

 

Single side lean code is usually either injector o-ring or loose manifold bolts. More rarely failed or plugged injector. I would start by swapping 02 sensor left to right just to verify it is not sensor.

 

Thanks for the suggestions, min01 & Extinct, I’ll do that sometime this week and give an update.