P0491 P0492 Insufficient Air flow
#1
AudiWorld Junior Member
Thread Starter
P0491 P0492 Insufficient Air flow
Hi all!
Hope I can find some help here.. Got a 2012 S4, check engine light came ON with the above two codes. Started to troubleshoot:
Has anybody seen anything like this before? Could it be that my ECU doesn't accept the command from the VCDS? I have been browsing for a while, and saw many people did the the pump check using "output test" - in my case such output test does not exist, I have to go in to "basic settings" and run a "checking secondary air injection system" command. Is it possible that this command does not activate the pump at all? If so, how should I check the pump in this case?
Any help is appreciated! Thank you
Andrey
Hope I can find some help here.. Got a 2012 S4, check engine light came ON with the above two codes. Started to troubleshoot:
- manually checked the air pump by applying 12 volts on it - it worked
- decided to run the pump using VCDS - Did not find an output test for secondary air injection system, went into the basic settings and found a command for checking secondary air injection system - it didn't not allow me to check the system while the ignition was ON - it said "aborted-safety reason:mulfuntion", I had to start the car and ran the command one more time, it worked afterwards and it said "runningperate brake pedal and depress acceleration pedal" - but I did not hear the pump running nor the relay clicking
- While the system check was running I disconnected the power connector from the pump and measured voltage on the contacts - there was 0 volts
- Checked 50A fuse, and it was OK
- Removed the relay, checked it and it was OK
- I wanted to see if the ECU is sending a signal to the relay to activate the pump, connected voltage meter to the power contacts in the relay socket and tried running a system check again - and again there was 0 volts on the power contacts in the relay socket
Has anybody seen anything like this before? Could it be that my ECU doesn't accept the command from the VCDS? I have been browsing for a while, and saw many people did the the pump check using "output test" - in my case such output test does not exist, I have to go in to "basic settings" and run a "checking secondary air injection system" command. Is it possible that this command does not activate the pump at all? If so, how should I check the pump in this case?
Any help is appreciated! Thank you
Andrey
The following users liked this post:
SapperVee1263 (06-13-2020)
#2
AudiWorld Member
Hey mate, are you referring to the electric barke vacuum pump, or the electric air injection pump. These are 2 seperate pumps on seperate circuits. One for the barkes the other for the exhaust manifold on cold start up. Just asking as you said the vcds tests advised to press the brake pedal, which shoudnt be necessary for the exhaust system circuits?
Thread
Thread Starter
Forum
Replies
Last Post
audifirst
A6 / S6 (C5 Platform) Discussion
2
04-16-2008 02:59 AM
leeep
A4 (B5 Platform) Discussion
4
08-19-2002 08:27 AM