Secondary Air System Help, P0491/492 error

[Redstick]

I have an 04 996TT Cab that with the P0491/492 error codes.  Looking to change the stock diverted valves out when I inspect all of the tubing. Any recommendation on what to use for a replacement.   Also is a there a DIY page for this replacement.  Any help is appreciated.

[Loren]

P0491 Secondary Air Injection System, Bank 1 – Below Limit

Possible fault cause
- Secondary air injection pump is not triggered
- Secondary air injection pump does not work
- Air supply lines restricted
- Electric change-over valve does not function
- Air change-over valve does not function
- Vacuum system leaking

 

P0492 Secondary Air Injection System, Bank 2 – Below Limit

Possible fault cause

- Secondary air injection pump is not triggered
- Secondary air injection pump does not work
- Air supply lines restricted
- Electric change-over valve does not function
- Air change-over valve does not function
- Vacuum system leaking

[Redstick]

we ended up replacing the pump as everything else was tested sat.  After the pump replacement, all of the codes cleared with no issue.  

[Loren]

[laalves]

I also had both for years. I did an overhaul of my SAI system during the COVID lockdown, replacing both of the 20-year old diverter valves with 710P from a VAG dealership (one of them did not hold any pressure), replaced all Pierburg electrovalves, Ts, Ys, Xs unions and some of the piping. Result: P0491 disappeared, P0492 still there. I can hear the pump working at startup, testing it with Durametric works fine, so that shouldn't be it.

 

Still scratching my head, but truth be told, I haven't done a leak check yet (which I should have done first) but already got the plugs to do it, just need to find the time.