Parts Catalog Accessories Catalog Tech Info Tech Forums
  Search our site:    
 Cart  | Project List | Order Status | Help    

Thread Post New Thread    Reply
Junior Member
Join Date: Aug 2005
Location: Rochester, NY
Posts: 1
Question Will Check Engine Reset After Air Pump Replacement?

I replaced the Secondary Air Pump and Air Pump Control Valves on a 1996 328i with OBD-II codes P1423 and P1421. Will the check engine light reset automatically?

The replacement pump and valve are operating correctly, no leaks in the vacuum lines. I've driven 180 miles, 16 engine restarts (5 cold starts) and several trips of either highway or city driving lasting over 15 minutes. But still the light stays on. Is clearing the only way?

OBD-II scan says there are no faults, but it still has a history of P1423 and P1421.

When I say cold start, I mean overnight cool-down, but the temperature is still 70F in the morning.

I believe the air pump vacuum check valve failed first. It was very coked and stuck open, and could not be unstuck despite many cleaning attempts with brake cleaner and WD-40. When I gave up, it would actuate, but not return to a sealed, normally closed position.

Next I discovered the air pump was dead. I was fooled because when I start the car, the air pump vibrates and the snorkel hose makes a sucking sound. The pump was dead, corrosion at connector and seized motor. Engine vibration made the pump shake. Stuck-open air pump vacuum check valve allowed air flow between snorkel and the exhaust manifold.

When OBD-II check engine light is cleared, it resets the computer. There are 8 (?) faults that go to an 'unknown' status until the car is driven and the history adds up. Either the history is OK, and the status changes from 'unknown' to 'pass'. Or, if 3 faults 'fail' or remain 'unknown' after some time, the check engine light will light.

Old 08-11-2005, 12:43 PM
  Recommend this thread for the PelicanWiki    Reply With Quote #1 (permalink)
Jeron's Avatar
Join Date: Feb 2004
Location: DFW (Hurst), Texas
Posts: 4,729
There are a few CEL's that will reset automatically but I think your codes fall into the more serious category that will not reset.

Some autoparts stores will check and reset CEL for free. Or join and contact your local BMW CCA.
HPDE Instructor (BMW / PCA / Apex)
Here: 1997 M3/4 Byzanz/Magma ~ 2006 Yamaha R6 ~ 1997 R1100RT ~ 1991 Ford F-150 5.8l ~ 2015 Kia Optima
Gone: 2001 330i Silver/Grey ~ 98 Camry V6 ~ 97 Camry I4 ~ 97 Mazda 626 I4 ~ 93 Sentra SE-R ~ 88 Toyota Truck I4
Old 08-12-2005, 08:31 AM
  Recommend this thread for the PelicanWiki    Reply With Quote #2 (permalink)
CEO, Pelican Parts Inc.
Wayne at Pelican Parts's Avatar
I don't think it will reset. Having one of these tools in your toolbox is very useful:


Wayne R. Dempsey, Founder, Pelican Parts Inc., and Author of:
101 Projects for Your BMW 3-Series 101 Projects for Your Porsche 911 How to Rebuild & Modify Porsche 911 Engines 101 Projects for Your Porsche Boxster & Cayman 101 Projects for Your Porsche 996 / 997
Coming in 2014:
101 Projects for Your MINI Cooper
Old 08-14-2005, 10:53 PM
  Recommend this thread for the PelicanWiki    Reply With Quote #3 (permalink)
Old 08-14-2005, 10:53 PM

Thread Tools
Rate This Thread
Rate This Thread:


All times are GMT -8. The time now is 06:20 PM.

Powered by vBulletin® Version 3.8.7
Copyright ©2000 - 2016, vBulletin Solutions, Inc.
Search Engine Optimization by vBSEO 3.6.0
Copyright 2011 Pelican Parts - Posts may be archived for display on the Pelican Parts Website -    DMCA Registered Agent Contact Page

DTO Garage Plus vBulletin Plugins by Drive Thru Online, Inc.