P0491 and P0492 wont go away

trhaverstock · #1 03-12-2018, 02:26 PM

Thanks for the lead. I am not getting good hits on an E53 X5 relay testing procedure. What other chassis has a similar relay (am seeing a lot of hits on e46) and where are the buggers located at?

Overboost · #2 03-12-2018, 02:33 PM

Quote:

Originally Posted by trhaverstock

Thanks for the lead. I am not getting good hits on an E53 X5 relay testing procedure. What other chassis has a similar relay (am seeing a lot of hits on e46) and where are the buggers located at?

Bridge pins 30 and 87, the pump should run

trhaverstock · #3 03-12-2018, 02:47 PM

You rock! Will test this when I get home from work tonight. Am I following your pic that the relay is roughly behind the windshield washer reservoir?

trhaverstock · #4 03-27-2018, 09:54 AM

I wasn't 100% sure about my relay test so I replaced it since it was cheap. Cleared the codes and they came back. So I suspected the check valve could be bad and replaced it (Pierburg). Cleared the codes and they came back again. I had previously removed the pump and connected it to 12VDC direct and it spins fine so I am scratching my head how that could be bad. This is a 2004 E53 3.0i manual trans and so the check valve does NOT have the vacuum line as the earlier models had with some other device in an unfriendly-to-replace location. Any wisdom on what to test next? I am throwing a P0491 and P0492. Thanks. T

Overboost · #5 03-27-2018, 10:41 AM

Quote:

Originally Posted by trhaverstock

I wasn't 100% sure about my relay test so I replaced it since it was cheap. Cleared the codes and they came back. So I suspected the check valve could be bad and replaced it (Pierburg). Cleared the codes and they came back again. I had previously removed the pump and connected it to 12VDC direct and it spins fine so I am scratching my head how that could be bad. This is a 2004 E53 3.0i manual trans and so the check valve does NOT have the vacuum line as the earlier models had with some other device in an unfriendly-to-replace location. Any wisdom on what to test next? I am throwing a P0491 and P0492. Thanks. T

Does the pump run in the morning at first fire up? It should run for about 30 seconds when cold. If it is running you could have a problem with the aux maf sensor connected to it.

https://youtu.be/NR84c_61C9I

trhaverstock · #6 03-27-2018, 11:01 AM

My secondary pump is -not- kicking on. Good lead on the secondary MAF. Regarding the video I do have a different code than his 1419, I'm getting 491/492. I did remove this the other week and my filter was pretty good. I shot the sensor with a little CRC MAF spray same as he had in the video. However, perhaps there is another test I can do rather than replace and pray on the secondary MAF (test with voltmeter or ??). Looks like that part, if 100% dead, is $60-75.

Overboost · #7 03-27-2018, 11:13 AM

Quote:

Originally Posted by trhaverstock

My secondary pump is -not- kicking on. Good lead on the secondary MAF. Regarding the video I do have a different code than his 1419, I'm getting 491/492. I did remove this the other week and my filter was pretty good. I shot the sensor with a little CRC MAF spray same as he had in the video. However, perhaps there is another test I can do rather than replace and pray on the secondary MAF (test with voltmeter or ??). Looks like that part, if 100% dead, is $60-75.

That pump has to run when cold. I read you replaced your relay and there is not much more to it than that. I would try bypassing the relay by a jumper between pin 30 and 87 to see if the pump runs.