P1423 - 002 Secondary Air Injection System; Bank 1 Insufficient Flow
05-13-2018, 07:39 PM
#1
AudiWorld Wiseguy
Thread Starter
SAI Insufficient Flow
P1423 - 002 Secondary Air Injection; Bank 1 Insufficient Flow.
‘04 BFM 4.2i V8 motor.
Anyone ever had this error and fixed it? There’s no noticeable symptoms other than the check engine light.
Is it most likely due to a gummed up Bank 1 combi-valve? I’m leaning away from a vacuum, solenoid, or SAI pump issue as both combi valves run off the same vacuum line and pump so faults there would, in theory, affect both banks equally. Additionally, engine module output tests all operate normally and don’t show any errors. SAI pump spins up etc.
So that’s my logic, anyone got any suggestions or tips on how to fix? The combi valves (particularly bank 1) look like a pain in the *** to get to. So is trying to get some carb cleaner/seafoam type treatment into the SAI lines to clear the combi-valve worth a shot before trying to disassemble and manually clean/replace?
Last edited by dvs_dave; 05-14-2018 at 08:32 PM.
05-16-2018, 10:42 AM
#2
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P1423 - 002 Secondary Air Injection; Bank 1 Insufficient Flow.
‘04 BFM 4.2i V8 motor.
Anyone ever had this error and fixed it? There’s no noticeable symptoms other than the check engine light.
Is it most likely due to a gummed up Bank 1 combi-valve? I’m leaning away from a vacuum, solenoid, or SAI pump issue as both combi valves run off the same vacuum line and pump so faults there would, in theory, affect both banks equally. Additionally, engine module output tests all operate normally and don’t show any errors. SAI pump spins up etc.
So that’s my logic, anyone got any suggestions or tips on how to fix? The combi valves (particularly bank 1) look like a pain in the *** to get to. So is trying to get some carb cleaner/seafoam type treatment into the SAI lines to clear the combi-valve worth a shot before trying to disassemble and manually clean/replace?
As far as long-term, this doesn't really affect much, other than your sanity looking at that CEL on your dash; or answering the same question over and over again every time someone gets in your car and glances over to your dash.
05-17-2018, 09:59 AM
#3
AudiWorld Wiseguy
Thread Starter
We have to pass emissions in IL, and this would be a fail. And as it’s coming up I need to get on it.
I looked up this thread from a while back that I remember contributing to, but annoyingly no resolution was posted.
https://www.audiworld.com/forums/a8-...ction-2922703/
It also seems like no one has ever had an issue with just the one bank. Seems to usually be both.
Anyway, I think I’ll buy a cheap vacuum pump for testing purposes and also spray some seafoam or similar into the system, see if that sorts it.
I looked up this thread from a while back that I remember contributing to, but annoyingly no resolution was posted.
https://www.audiworld.com/forums/a8-...ction-2922703/
It also seems like no one has ever had an issue with just the one bank. Seems to usually be both.
Anyway, I think I’ll buy a cheap vacuum pump for testing purposes and also spray some seafoam or similar into the system, see if that sorts it.
05-17-2018, 10:34 AM
#4
AudiWorld Super User
Been a long time since my 2000 A6 4.2. That used to rot the pretty German braided vacuum hose like no tomorrow, until I finally ripped it all out for the NAPA off the reel good stuff. IIRC, if the hose is cracked open near the end toward a combi valve, it is small enough diameter that the vacuum may still pull the other side even with a slight leak. Close hose inspection and maybe replace it all given the age would be my first low cost and easy try. If in there, the idle also gets just a little uneven from my C5 experience, if you are sensitive to that. On C5 4.2 they opened a vacuum solenoid switch under the intake cover area where the Y effectively was for the two combi valves; that cover was just the ticket for yet more hose cooking too.
Yes could be the combi valve. On an S8 or W12 you can get the one side stuff routinely since they use two independent pumps; thus I had to think back to 4.2. Combi valve would probably be next stop after (still) a hose check. On some motors like 3.2 you can get into clogged ports and fouling issues; I don't know D3 compared to C5 differences there since on D3 and C6 they had to move the cats into the manifold area. They tweaked things generally to get past tightened up emissions specs that first hit in 2004 that required faster cat light off in particular--how SAI comes into it and why even the pre-2004 4.2 info may not be fully on point.
Yes could be the combi valve. On an S8 or W12 you can get the one side stuff routinely since they use two independent pumps; thus I had to think back to 4.2. Combi valve would probably be next stop after (still) a hose check. On some motors like 3.2 you can get into clogged ports and fouling issues; I don't know D3 compared to C5 differences there since on D3 and C6 they had to move the cats into the manifold area. They tweaked things generally to get past tightened up emissions specs that first hit in 2004 that required faster cat light off in particular--how SAI comes into it and why even the pre-2004 4.2 info may not be fully on point.
Last edited by MP4.2+6.0; 05-17-2018 at 10:38 AM.
05-19-2018, 01:28 PM
#5
AudiWorld Wiseguy
Thread Starter
So I’ve narrowed it down and found the problem to be a blown diaphragm in the bank 1 combi valve. It won’t hold a vacuum and I can hear it hissing when I connect up my vacuum pump. I pulled the vacuum lines and tested them and they were all still in good shape (and then promptly dropped one into the depths, never to be seen again...another story)
So to replace the bank 1 combi valve (US passenger side) looks like a nightmare as it’s pretty buried; the sort of job I’d gladly pay someone else to do! However if any one has any tips to make the job easier than it appears, I’d be grateful to hear them!
So to replace the bank 1 combi valve (US passenger side) looks like a nightmare as it’s pretty buried; the sort of job I’d gladly pay someone else to do! However if any one has any tips to make the job easier than it appears, I’d be grateful to hear them!
Last edited by dvs_dave; 05-29-2018 at 09:09 AM.
05-28-2018, 04:40 PM
#6
AudiWorld Wiseguy
Thread Starter
Picked the car up on Friday after heeding the advice in the linked thread above that this is a PITA diy job and well worth paying someone else $300 to do. Hopefully I’m not tempting fate, but I’ve been on a few decent drives since and no check engine light....yet. Let’s hope it passes the SAI readiness check, which I think can take a while to complete.
05-28-2018, 09:10 PM
#7
AudiWorld Super User
Picked the car up on Friday after heeding the advice in the linked thread above that this is a PITA diy job and well worth paying someone else $300 to do. Hopefully I’m not tempting fate, but I’ve been on a few decent drives since and no check engine light....yet. Let’s hope it passes the SAI readiness check, which I think can take a while to complete.
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05-29-2018, 08:44 AM
#8
AudiWorld Wiseguy
Thread Starter
If that’s all it takes, then I should be good to go. Done at least 7 hot/cold/hot cycles since and driven over 100 miles on the highway.
Not gotten round to plugging in VCDS to check for sure, but not inclined to either unless the check engine light comes back on.
Not gotten round to plugging in VCDS to check for sure, but not inclined to either unless the check engine light comes back on.
05-16-2019, 08:47 PM
#9
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Try new MAF, if your combivalves work, and you have both banks failing secondary air.
I just thought I would chime in.
I had both banks of secondary air injection giving me failed Readiness.
(I couldn't pass Smog at the California Start Station to renew my registration)
- I replaced my MAF and was immediately able to get secondary air injection to pass Readiness.
My EGR/combivalves both seem to work.
I had both banks of secondary air injection giving me failed Readiness.
(I couldn't pass Smog at the California Start Station to renew my registration)
- I replaced my MAF and was immediately able to get secondary air injection to pass Readiness.
My EGR/combivalves both seem to work.
05-18-2019, 08:47 AM
#10
AudiWorld Wiseguy
Thread Starter
I fixed this a while ago. One of the combi-valves had failed and needed replacing. Got my local shop to do it as it’s a pain in the *** job. Glad I did too as the new one they fitted failed within a week (again was a failed vacuum diaphragm). Of course the repair was under warranty so happy days.
SAI readiness completed, IL emissions test passed and been good ever since.
SAI readiness completed, IL emissions test passed and been good ever since.
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