Emissions/ SAI system

Tiny
COLLISION BOB
  • MEMBER
  • 2004 AUDI A6
  • 78,000 MILES
Hi Everyone. Here it is: Car is a 04 A6Q w/2.7 BEL engine

1.) CEL on
2.) Scanned / 3 codes.#17862/ 17819/ 17831
3.) Checked circuit fuses, tested pump relay. All tested good
4.) Checked for voltage at SAI pump, 12v at pump but pump inoperative
5.) Removed pump & took apart
6.) Pump was seized and burnt at motor brush locations/ housing w/small
amount of melt. Plastic brush holder in motor completely fried.
7.) Bought & installed new pump / cleared codes
8.) New pump failed within 50 miles
9.) Tested new pump. Isolated it, applied 12v, inoperative
10.) Scanned system, same codes found


Notes: On engine shut down after initial test drive noticed SAI pump was
running with engine off. Thought this was odd.

Question: Would a bad exhaust gas temp sensor in bank #1 cause the OEM
pump to fry?
How do I test this sensor with a DVOM & what are the specs that
I need to look for?
Do you
have the same problem?
Yes
No
Sunday, April 21st, 2013 AT 9:07 AM

3 Replies

Tiny
ASEMASTER6371
  • MECHANIC
  • 52,797 POSTS
Does this have a check valve for the exhaust?

The pump may be failing from excessive pressure backing into the pump.

Also, check the cat converter back pressure to be sure the engine is breathing out the back and not back to the pump

Roy
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Sunday, April 21st, 2013 AT 10:36 AM
Tiny
COLLISION BOB
  • MEMBER
  • 2 POSTS
Hey Roy.
This engine uses three check valves in the SAI system. One check vavle is used to regualate vacuum. The other two are called combination valves :one for each bank of cylinders.
Thanx, C/Bob
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Sunday, April 21st, 2013 AT 1:30 PM
Tiny
ASEMASTER6371
  • MECHANIC
  • 52,797 POSTS
I would be looking at these valves allowing exhaust back to the pump

Roy
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Sunday, April 21st, 2013 AT 3:06 PM

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