3-Series (E46, E90)Chat relating to the BMW 3-Series from 1999 to Current. Models include: BMW 316i, BMW 318i, BMW 318Ci, BMW 320i, BMW 323i, BMW 325i, BMW 330i, BMW 328 Ci, BMW 328i, BMW 325i/xi, BMW 330Ci, BMW 320d, BMW 330d, BMW 335d.
BimmerWerkz.com is the premier BMW Forum on the internet. Registered Users do not see the above ads.
Originally posted by oscaroc@Feb 5 2005, 06:47 PM My car won't start it is a 01 325i auto and it threw two codes P0491 and P0492 can anyone help? thanks
[snapback]286602[/snapback]
Respond with the last 7 digits of your vin # and i can decode those for you.
P0491 Secondary Air Injection System Insufficient Flow (Bank 1)
P0492 Secondary Air Injection System Insufficient Flow (Bank 2)
Those are the faults.... if the car is not starting this is not the cause. Most likely the codes are alerting you as to a failed secondary airpump. If you find that it is indeed failed then check and/or replace the 1 way valve which goes inline with the pump.
Once again this will not cause a no-start condition. Does the engine crank over but not start? Or is it not cranking at all? Have you tried jump starting etc? Give us some more info on what its doing and maybe somebody can help.
It does cranks but it never fires, it gets close but no cigar. Thanks for the info too by the way. I appreciate it. The only thing I have done with the car in the last week is drive it to put gas in it. i would like to find what is wrong it is very peculiar
Perhaps a bad fuel pump? You can try having some1 else crank over the car while u lay down and pound on the fuel tank a bit with a rubber mallet or the palm of your hand and see if it fires. Sometimes this will jar the pump into working. Or if you wanted to get technical you could use a guage to check the fuel pressure. :P
If you have fuel pressure of course the next thing to check would be spark.
And of course if worse comes to worse you can always take it to a professional and have it diagnosed.
Best of Luck
Originally posted by Dirty_Tool@Feb 6 2005, 07:19 PM P0491 Secondary Air Injection System Insufficient Flow (Bank 1)
P0492 Secondary Air Injection System Insufficient Flow (Bank 2)
Those are the faults.... if the car is not starting this is not the cause. Most likely the codes are alerting you as to a failed secondary airpump. If you find that it is indeed failed then check and/or replace the 1 way valve which goes inline with the pump.
Once again this will not cause a no-start condition. Does the engine crank over but not start? Or is it not cranking at all? Have you tried jump starting etc? Give us some more info on what its doing and maybe somebody can help.
DT
[snapback]286993[/snapback]
I too have the same exact codes. Just read today at Schucks Auto on My 2001 325 xi with 34,000 miles. My Service Engine Light has been on for about 3 days now, but the car seems to be running just fine. Any ideas for an easy check or fix before taking it into a pro?
Originally posted by mark1411+Feb 7 2005, 05:02 PM--><div class='quotetop'>QUOTE(mark1411 @ Feb 7 2005, 05:02 PM)</div><div class='quotemain'><!--QuoteBegin-Dirty_Tool@Feb 6 2005, 07:19 PM P0491** Secondary Air Injection System Insufficient Flow (Bank 1)
P0492** Secondary Air Injection System Insufficient Flow (Bank 2)
Those are the faults.... if the car is not starting this is not the cause. Most likely the codes are alerting you as to a failed secondary airpump. If you find that it is indeed failed then check and/or replace the 1 way valve which goes inline with the pump.
Once again this will not cause a no-start condition. Does the engine crank over but not start? Or is it not cranking at all? Have you tried jump starting etc? Give us some more info on what its doing and maybe somebody can help.
DT
[snapback]286993[/snapback]
I too have the same exact codes. Just read today at Schucks Auto on My 2001 325 xi with 34,000 miles. My Service Engine Light has been on for about 3 days now, but the car seems to be running just fine. Any ideas for an easy check or fix before taking it into a pro?
Thanksl
Mark
[snapback]287585[/snapback]
[/b][/quote]
Mark,
Once again this is most commonly a failed pump. Check fuses # 3 and #36. If they are good you can try jumping the secondary air pump relay (behind RH footwell trim) and seeing if the pump runs. If it doesnt run confirm it has power and ground and if so replace the pump, as well as the 1 way valve. The 1 way valve often causes pump failure by allowing condensation into the pump.
Note: fuses and component location are for E46 and should be confirmed in the Bentley manual for anyones specific vehicle. Do not take my word for it
I've check the necessary fuse #36 and it is o.k. I'm not sure how to jump the relay to see if the pump works and or test for power and ground. But I may be able to change the pump and valve. Is that pretty straight forward?
Also, should I be hearing the secondary air pump turn on every cold start? And is it o.k. to drive the car for awhile with a broken secondary air pump?
I was told that if your secondary air system is non operational that it would be the cause of not being able to cold start the vehicle. But that doesn't seem right it should still fire even it it runs crappy. I could be wrong
Do i need to crank the the motor over to check fuel pressure? Or just turn the key and take a reading?
I know i need to get the bently book! I have an audi A4 book but that doesn't help any here
Originally posted by mark1411@Feb 7 2005, 09:12 PM Thanks DT.
I've check the necessary fuse #36 and it is o.k. I'm not sure how to jump the relay to see if the pump works and or test for power and ground. But I may be able to change the pump and valve. Is that pretty straight forward?
Also, should I be hearing the secondary air pump turn on every cold start? And is it o.k. to drive the car for awhile with a broken secondary air pump?
Thanks again for you help.
Mark
[snapback]287742[/snapback]
Its a really straightforward job to replace the valve and pump. It wont hurt the car at all to run it for a while without the pump, this is a smog component which only runs during the 1st 90 secs of engine warmup anyway. Yes you should hear it on every cold start.
DT
Originally posted by oscaroc@Feb 8 2005, 06:30 AM Yeah thanks for your help it is appreciated.
I was told that if your secondary air system is non operational that it would be the cause of not being able to cold start the vehicle. But that doesn't seem right it should still fire even it it runs crappy. I could be wrong
Do i need to crank the the motor over to check fuel pressure? Or just turn the key and take a reading?
I know i need to get the bently book! I have an audi A4 book but that doesn't help any here
[snapback]287838[/snapback]
Yes check fuel pressure while cranking, not just with the key on. Secondary air pump will absolutely not cause a no start condition or even a rough running condition. Merely a smog component.
DT
I can hear the pump noise on cold start up and can even feel air running through hose, so I'm going to assume it was a momentary fault of some kind that set off the service engine soon light.
I just got a Peake scan tool and turned off the SES light, so lets hope it stays that way. By the way do you think the Peake scanner is a good one? Thanks again.
The AutoGuide.com network consists of the largest network of enthusiast-owned enthusiast-operated automotive communities.
AutoGuide.com provides the latest car reviews, auto show coverage, new car prices, and automotive news. The AutoGuide network operates more than 100 automotive forums where our users consult peers for shopping information and advice, and share opinions as a community.
I have an audi A4 book but that doesn't help any here 
Linear Mode
