P0492 - Maybe caused by O2 sensor?

[ProfessorX5]

I've read this could be caused by bad hoses or the O2 sensor, which I'm going to replace as soon as the part gets here. Any clues?

I'm hoping it's not the air pump itself, though from what I've read so far if it was that it'd set a p0491 too. All I've got is the p0155 and p0492.


I sure wish my 02 sensors would get here already!

[ProfessorX5]

Swapped out the O2 sensor, CEL still on, but will see if it clears by itself.

[tmv]

NO, the O2 sensor does NOT trigger P0492.

OBD Code P0492refers to Secondary Air Injection System Insufficient Flow
Symptoms
- Check Engine Light ON (or Service Engine Soon Warning Light)
Causes
- Intake leak - Damaged AIR system components - Faulty AIR Solenoid Valve - Faulty AIR system relay

Try to clear the code and see if it comes back.

[upallnight]

Check to see if the plastic hoses are on tight from the air pump.

[ProfessorX5]

Hmm will check the hoses.

[Doru]

For the secondary air system, what starts causing the problems are these things:

• sticky air valve. p/n 11727540471. In time it gets clogged with carbon deposits combined with condensation, and the internal valve gets sticky. One "could" clean it (after it's removed) with brake cleaner or similar, but the best way is to change that part. You will need also a new gasket p/n 11727505259. The gasket is like a "sandwich" with 3 layers. Part of the old one might stick to the engine block when removed.
• sticky "salmon" relay p/n 12631742690 - this could lead to the SAP to stick in the "on" position and fry the pump (expensive to replace).

Usually these 2 items "should" be changed every 80 k miles to avoid those annoying SAP codes, or worse an expensive SAP replacement.

I did this on my e39 couple years back and it's very easy to do.

[ProfessorX5]

The corrugated plastic hose seems okay, but when the pump is running, I can feel an air current near the air cleaner, so I suspect it's that hose (#7).

@Doru I may as well replace the valve then, since it probably hasn't been done in a long time. TY!