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P0411 SAIP easy fix

77K views 16 replies 10 participants last post by  e_identity 
#1 ·
For only the second time in 8 years of ownership my 2002 AWM threw a CEL. A quick scan showed the only code was for the SAIP.

If you start your car in a garage, it's easy to hear the faint whir of the SAIP a few seconds after start-up. With the door open, you can also see the interior lights slightly dim. Mine no longer did either so it was time to find the problem.
First of all you should look for the obvious issues like bad vacumn lines to the combi valve or hose connections near the pump but it was pretty clear I had a electrical issue. Applying 12v to the pump showed it was working just fine. Off to to ECU box.


Power was fine at the 373 relay and the fuse tested okay. The easy part of this fix comes from knowing the SAIP had twice stayed on after driving more than 30 minutes, even after turning the ignition off. A quick search showed the relay was the usual suspect. A test applying voltage to the relay confirmed it wasn't working right. The local parts store had the $5 relay as I didn't have the time to order one online. My only question is why the updated VW oem relay is $35, pn 8K0951253, and why was it updated? It's only a standard 4 blade bosch relay. So far after a week the CEL is history but I will pick up a few spare meyle relays on the next parts order.
 
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#3 ·
It is a fairly hefty relay, 40amp irrc, so maybe that's their reason for the cost. Was your autoparts relay rated that high? Rule of thumb with relay circuits, if it isn't shutting off when power is no longer supplied to the relay coil, it's almost always the relay sticking.
 
#4 ·
Replacement relay is also 40 amp and actually felt more beefy than the OEM. The parts guy really went the extra mile to find the correct relay. He went to his master electronics catalog and found it by doing a picture match as none of the parts seaches show anything for a VW air pump relay.
Too bad my old DRL wouldn't fit as I kept it around just in case. I guess it just follows VW pricing strategy , think of an outrageous price and then triple it.
 
#5 ·
I also have a 2001 V6 engine passat that is giving me some problem. The car was not driving well and the CEL came on. A quick scan showed codes P0411 & P0423. I changed all the vacuum hose, but the CEL is still on with the same codes. The main problem now is that the car will not start unless someone jump start it. Each time I tried to start the car the bash board light comes on and I can hear a clicking sound around the ECU box and also a whirling sound around the power steering fluid reservoir. The battery is new. Can anyone tell me what my problem is?
 
#7 ·
Sorry, I threw out the reciept on the new relay but the one thing I didn't like was it was made in China. That may not be such a bad thing as VW electronics are only slightly better than Lucas. Just order some of those Meyle relays from Autohausaz.

Memuna, your problem seems more involved than a air pump issue but let me see if I can find anything to help.

Mark
 
#8 ·
Mark,

Looks like we have the same car. A few days ago, after driving about 30 mins at highway speeds, I see the CEL blink a couple times just as I was getting off the exit. No noticeable change in performance though, and got to destination fine. The CEL was off at this point.

Then when restarting after 20 minutes or so, the car had a little hesitation at low speeds. The next day, I see the CEL come on, and go to AutoZone to pull the codes. There were two: the one in question, P0411, and P0304: Cylinder 4 misfire condition. I'm hoping they are related, but I'm not sure.

I definitely get hesitation (read "misfire"?) at cold start. I checked the fuse and looked fine and was reading battery voltage across it when I started the car cold. The small vacuum hose from the combi-valve to the engine is fine; in fact I replaced that a year or so ago.

So I got under the car, removed the shroud and took a look at the SAIP. The two flex hoses to/fro the SAIP looked fine. I removed them from the pump, removed the electrical connection to the SAIP, and removed the pump itself, which is now sitting on my bench. What do I do next? Do I apply battery voltage to the SAIP terminals (which is + and which is -)? Or do you recommend anything else?

Thanks so much in advance for any advice.

-Mark
 
#9 ·
Update: applying battery voltage to pump after clamping it to bench showed that it was working just fine: vacuum at inlet and pressure at outlet. So I think I can at least rule out the pump. I want to hook my multimeter to the SAIP electrical connector and start it cold, just to ensure that it's getting power at the right time. If so, I think I'm looking at a combination valve problem then, right? Anything else?
 
#10 ·
It seems that if you see multiple codes like this it's unlikely the air pump is to blame but go ahead and check to see if power is making it to the pump at startup.
Although uncommon, the combi valve usually fails in the open position so if you fashion a system to blow air towards the valve you should feel resistance. Applying vacuum to the combi should obviously allow you to blow through it freely. The other part that could fail is the N112 change over valve located under the intake I believe.
The great unknown to me is how the misfire and hesitation issues seem to trigger the P0411 code with the other codes. Must be the rich condition from the mis-fire is playing havoc with the cat and 02 sensors. Anyone have more insight?
Mark
 
#11 ·
Solved

For the sake of closure here, and if it's of any benefit to others, I solved my particular problem.

The P0411 seemed to be a red herring/symptom in this case. The P0304 (cylinder 4 misfire), however, was the more relevant code. When I pulled the ignition coil on that cylinder, thinking the coil itself may have failed [as has happened several times before], I discovered that in fact the spark plug was broken. I have never seen this before, and neither had the guys at two different auto parts stores. The actual plug (ceramic) part had somehow dislodged from the mount, so it would bounce up and down and hence misfire most of the time. This was a Champion [apparently cheap] spark plug I had put in a year or so ago. So I took the opportunity to replace all spark plugs with NGK Iridiums. After just a day of driving, the CEL put itself out.
 
#13 ·
I'm working on the steps to isolate the P0411 problem on my 2000 1.8T Passat. My goal is to get the car to pass emissions here in Austin.

Current status:
1) Replaced vacuum hoses
2) Inspected other hoses they look fine
3) Secondary air pump runs for 60+ seconds during cold start

A couple questions:
1) If the secondary air pump runs, can the failure still be the combi valve?
2) Steps to check secondary air pump selenoid?
3) Steps to check fuses in ECM box?

Other thoughts or ideas to isolate?

I've already been through three secondary air pumps and a combi valve. I'd like understand so I don't have to continue to deal with this issue.
 
#16 ·
That is a strange issue to be sure with no power to the relay. Even the Bentley manual only mentions that the SAIP is triggered by the ECU but makes no mention of any other fuses other than the fuse and relay in the ECU box. It might help to describe your issue with the SAIP and if you are throwing any more codes than P0411. Multiple codes could point you in a different direction. If anyone has more insight to this please speak up.

Mark
 
#17 ·
10.5 volts to relay? Relay p/n?

P0411 Code on 2003 Passat 1.8T AWM B5.5
Cold start, SAIP did not run.
Vacuum lines connected and appear good.
Voltmeter reads no current to SAIP at startup.
Check Relay [stamped 373 on top, p/n 8D0 951 253 A]
4 pins: 85/86 10.5V at startup (relay removed, voltmeter probes to female connectors in ECU box).
30/87 infinite ohms, 0.00 volts at startup (worked voltmeter probes under relay w/o removing relay to test).
0.00 volts at 40A fuse (engine on) -- fuse tests good.
Remove relay, connect 85/86 to battery directly, I hear relay click and 30/87 are connected.
Connect battery directly to SAIP, SAIP runs.
Root around in my tool box and find a 30A 4pin relay to install as temp fix.
Clear codes, start car 3 times -- code hasn't come back yet. [full disclosure -- I didn't verify that SAIP was running].
Two questions:

1) at 1stVW, put in the vw p/n for the relay and it came up with p/n 4H0 951 253 A. Is this an adequate substitute?

2) Is the fact that I had only 10.5 V at 85/86 a problem? I expected appx. 12 to 14 volts. The old relay seemed to work with more voltage.

Thanks for all the help!

e identity
 
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