Need Help Solving P01421 CEL code

[smhapp]

All

I've read a few posts on this issue but frankly don't want to throw a lot of parts at the problem without a little guidance. I have a 1999 328i with roughly 88K miles on it (original owner). The CEL code is a P1421 which according to my friends at autozone the problem is a secondary air pump, bank 2 issue. everything i've read says that you should replace the pump and valve together. Gas mileage has been crappy for a while and I've never replaced the oxygen sensors.

Should i replace the secondary pump AND valve and see if it clears first or start with the oxygen sensors? Any advice for how to proceed? I hate to throw parts at this problem

Thanks in advance!

S

[Pelican Parts]

Hello and welcome to the forum! I'm attaching a link to our site's DIY tech article on this issue. Please let us know if you have any questions!

http://www.pelicanparts.com/BMW/tech...Components.htm

[smhapp]

Thanks for the post. the issue is the vacuum tube to the check valve. I've identified this as part number 11657803732 but would love confirmation. Any step by step DIY with pics out there for me to reference? I think it is one piece of hose that plugs into a connector on the same side as the check valve. I don't think other sections of the vacuum line need to be replaced because these are separate sections run from the connector. But is this true?

Again thanks in advance for any help

[Honolulu]

The real question is, rather than linking to a DIY to change a part, how does one tell whether the part is, in fact, faulty?

Where is the sensor that triggers the fault code, and what is the sensor function (what does it sense?)

Without knowledge of the subsystem and its correct function, one is simply throwing parts at the code, EXACTLY WHAT THE OP WANTS TO AVOID.

[MIKYZZ4]

Thanks for the post. the issue is the vacuum tube to the check valve. I've identified this as part number 11657803732 but would love confirmation. Any step by step DIY with pics out there for me to reference? I think it is one piece of hose that plugs into a connector on the same side as the check valve. I don't think other sections of the vacuum line need to be replaced because these are separate sections run from the connector. But is this true?

Again thanks in advance for any help

This diagram should help you identify the different parts in the system:http://www.realoem.com/bmw/enUS/show...diagId=11_2203
Diagnostic scans performed with AutoZone generic scan tools are very unreliable when it comes to BMW diagnosis.
A BMW specific scan tool will give more accurate results.
Read this helpful PDF.page#6, to understand and test the system,
here is the link:https://www.bavauto.com/newsletter/2...newsletter.pdf

[smhapp]

Thanks all! Turned out to be an obvious issue and extremely easy fix. Vacuum hose replacement off the check valve. Took 30 minutes, tops! Thanks to my friends at Baker auto parts here in the Atl for selling it to me at a reasonable price. check engine light turned off. I've invested in the peake tool -- too many issues with an 18 year old car to guess at future fixes.

[MIKYZZ4]

Thanks for the update, glad it was an easy fix!