Help please! P0491 and P0492

[sigtwenty]

You dont have to remove the seat but you can unbolt it and tilt it back.

If the pump is actually turning on its not likely your pump. Basically the air pump injects air into the exhaust to lean it out when cold. O2 reads this information.

Could be carb build up, bad fuse, vacuum leak.

[bcain79]

You dont have to remove the seat but you can unbolt it and tilt it back.

If the pump is actually turning on its not likely your pump. Basically the air pump injects air into the exhaust to lean it out when cold. O2 reads this information.

Could be carb build up, bad fuse, vacuum leak.

Could it be because of bad o2's?

[noodlesandsam]

Probably not. O2 sensors get their own monitoring and error codes. These are specific to the pump.

[bcain79]

So, when I reset the light it will stay off for a couple days and then come back on. If it was my relay wouldn't it instantly set off the CEL as soon as I reset the code?

[sigtwenty]

It comes back because the system is doing its self checks in not ready status. Once it goes into ready status it triggers the light.

If it was a fuse, logically, it should trigger the light right away as the circuit is not closed, like it was unplugged for example. But....Considering these codes are in both banks and is fairly generic it brings me to think its power to the unit thats not functional...
I have heard carbon buildup can cause this, and also a plugged cat can as well but those should throw a insufficient flow code not a general code like these.
One could still check for a vacuum leak on a hose that goes directly to or near it to be safe if these cars have such a thing.....but that usually cures p0410 code.

Consider this. A p0410 code is a code that says secondary air injection. Your codes specific to both banks...

All I know on my mercedes this system is a pita. Glad for my pre facelift model not having this system. Its a nightmare. And sadly only functions when car is cold. Once car is in closed loop it is not functional unless it detects a rich condition and it may kick in to lean out the exhaust.

[bcain79]

It comes back because the system is doing its self checks in not ready status. Once it goes into ready status it triggers the light.

If it was a fuse, logically, it should trigger the light right away as the circuit is not closed, like it was unplugged for example. But....Considering these codes are in both banks and is fairly generic it brings me to think its power to the unit thats not functional...
I have heard carbon buildup can cause this, and also a plugged cat can as well but those should throw a insufficient flow code not a general code like these.
One could still check for a vacuum leak on a hose that goes directly to or near it to be safe if these cars have such a thing.....but that usually cures p0410 code.

Consider this. A p0410 code is a code that says secondary air injection. Your codes specific to both banks...

All I know on my mercedes this system is a pita. Glad for my pre facelift model not having this system. Its a nightmare. And sadly only functions when car is cold. Once car is in closed loop it is not functional unless it detects a rich condition and it may kick in to lean out the exhaust.

Great info, thank you. For the past month I've been fighting a P0430 code (bank2). I put in new plugs and that day these 2 new codes popped up. I'm thinking I need to just replace all 4 o2's before I replace the cat, then replace the relay. Does this sound like a good plan?

[bcain79]

If you have a multi meter check for voltage at the secondary air pump connector. if no voltage is present then check for voltage at the relay and so on down the line. Do you have the ETM? (electronic troubleshooting manual)

It is very helpful in troubleshooting electrical problems and tracing back the source of power to a failure point.

Thanks, I'll start here. From what people are saying it seems my relay is likely the culprit since both codes popped at the same time.

[bcain79]

If you have a multi meter check for voltage at the secondary air pump connector. if no voltage is present then check for voltage at the relay and so on down the line. Do you have the ETM? (electronic troubleshooting manual)

It is very helpful in troubleshooting electrical problems and tracing back the source of power to a failure point.

Okay...2 months later (I recovered from surgery) and now i'm ready to tackle this problem this week. I'll check back in with you guys and let you know what I find ... this thread is a life saver! Wish me luck.

I have learned that the 50a BMW part number is PN 61138365901 and at NAPA it is PN 782-1144.

[bcain79]

UPDATE:

I was talking to my friend who is a machanic and told him what my car was doing and he said the relay didn't make sense but a vacuum leak did. So I checked all my vacuum lines and I missed somthing, I found the problem one of my lines on the back side of the motor was broke and litterally disinigrated. I bought a new line ($0.47) and put it in and the check engine light has not come on yet (it's only been 2 days).

(it was the back part of the #4 line that hooks to #5)

[Rhein Amacher]

Hmm mine is acting up as well.

[THE MAKER]

Okay...2 months later (I recovered from surgery) and now i'm ready to tackle this problem this week. I'll check back in with you guys and let you know what I find ... this thread is a life saver! Wish me luck.

I have learned that the 50a BMW part number is PN 61138365901 and at NAPA it is PN 782-1144.

Was it the 50 amp under the pass seat and is it the same for the e38 i have codes p0491 and p0492 and a p1349?

[THE MAKER]

Was it the 50 amp under the pass seat and is it the same for the e38 i have codes p0491 and p0492 and a p1349?

I replace the coil.unhooked went under the seat checked the seat check the 50 amp and it was good however I noticed the mech was messing with the black box to the right he unsnapped some of the clips hanging then put it back together then he snapped it back together then we plugged up the computer and now the computer is not reading however the misfire is gone so I disconnected and re connected the battery and I'm waiting for the CEL to come back on the code reader is not communicating with the vehicle checked by obd inside the car and under the hood I hope he didn't make another problem. Still waking for SES light to come on but glad the misfire is gone. I love it when there's no CEL on

[jjc034]

Hey,

So I am facing the p4091/p4092 codes and cannot pass emissions like this. I replaced the 50a fuse and relay, the CEL turned off, the pump came on VERY LOUDLY for a good amount of time, and then a few hours later the pump no longer turned on and the CEL returned.

Next step in my mind is to replace the valve and air pump, and check the hoses - does that make sense? If it is the hoses, can I replace them with generic ones from the auto parts store or do they have to be genuine BMW?

Thanks,
John

[clarkitect]

Check to see that the hose from the secondary air pump to the valve is not broken or loosly connected. This would explain the loud noise and codes.

[jjc034]

Check to see that the hose from the secondary air pump to the valve is not broken or loosly connected. This would explain the loud noise and codes.

So I pulled all the hosing and the valve minus the metal pump hose. Upon removing the valve I realized that the inside of the valve is wet and the hose is too. Thoughts on fixing this? Do I need to pull and re- seal the the metal tube?

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[clarkitect]

Good question. Hopefully someone can offer insight to the moisture in there. Maybe condensation? Your valve looks pretty gunky. Try cleaning out the valve and see if it helps. You could also pull the metal tube and clean it out but it’d be easy to start with the valve.

[jjc034]

Good question. Hopefully someone can offer insight to the moisture in there. Maybe condensation? Your valve looks pretty gunky. Try cleaning out the valve and see if it helps. You could also pull the metal tube and clean it out but it’d be easy to start with the valve.

Yeah I'm ordering a new valve but may test the old one. When I suck it does move freely

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[jjc034]

Good question. Hopefully someone can offer insight to the moisture in there. Maybe condensation? Your valve looks pretty gunky. Try cleaning out the valve and see if it helps. You could also pull the metal tube and clean it out but it’d be easy to start with the valve.

One other thing I noticed is this white/black vacuum hose was off and the nipple seems to have broken off the black canister. Anyone know what this is? It probably hasn't been helping the situation.

Lastly, the plastic hose is very brittle and likely cracked at the ribbed sections. Can I replace this with rubber heater hose in the same shape? Save a little $$$

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[clarkitect]

Might as well check the tube then. Make sure it’s clear. The hoses all in good condition?

[jjc034]

Might as well check the tube then. Make sure it’s clear. The hoses all in good condition?

The hoses from intake to SAS pump are beautiful. Plastic one seems very dry and made crinkling sound when I bent a little. I want to replace that but don't feel like dropping $70 if I don't have to. I was thinking I could do 1/2" hose, but wasn't sure if heater hose would collapse - it isn't vacuum though, blown air right?

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[clarkitect]

One other thing I noticed is this white/black vacuum hose was off and the nipple seems to have broken off the black canister. Anyone know what this is? It probably hasn't been helping the situation.

Lastly, the plastic hose is very brittle and likely cracked at the ribbed sections. Can I replace this with rubber heater hose in the same shape? Save a little $$$

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Missed this post. Looks like you’ve found the problem. Replace all the parts with the right replacement parts. Look at realoem.com for part numbers.

[jjc034]

Missed this post. Looks like you’ve found the problem. Replace all the parts with the right replacement parts. Look at realoem.com for part numbers.

Should I be concerned about that condensation though? I guess I'll just try to wet dry Vac it out

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[clarkitect]

The hoses from intake to SAS pump are beautiful. Plastic one seems very dry and made crinkling sound when I bent a little. I want to replace that but don't feel like dropping $70 if I don't have to. I was thinking I could do 1/2" hose, but wasn't sure if heater hose would collapse - it isn't vacuum though, blown air right?

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Yeah it's air pumped into the exhaust system. Some regular hose and clamps might work. But it may just be that the valve is not opening due to the broken nipple on the vacuum container, causing the air to leak out of the hose. Try fixing that first, or if you have a vacuum pump manually open the valve and see if the noise subsides.

Should I be concerned about that condensation though? I guess I'll just try to wet dry Vac it out

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I wouldn't be too concerned. Once you get it working again I would guess there'd be no more condensation.

[jjc034]

So just rechecked my emissions test - fixing the vacuum leak and stuff will remedy the codes, but will it make the cats, Evap, and O2 sensors ready?

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[jjc034]

So just rechecked my emissions test - fixing the vacuum leak and stuff will remedy the codes, but will it make the cats, Evap, and O2 sensors ready?

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So I solved my issues for all those wondering. For the two air bank codes, I originally replaced the fuse and relay but then the SAS pump sounded like a jet engine and crapped out. The more I dig into it, I realized the black vacuum canister on top of the intake manifold had broken. I bought a new canister, replaced the vacuum lines, and refreshed the SAS with new o rings on the pipe, new valve, ebay pump, and new plastic hose to the pump. All these got me to get a "ready" for SAS.

The next issue was Evap with the infamous p0453 code, indicating a voltage issue. I took off the rear driver fender liner and sure enough, the wires were routed outside of the large hose, causing them to chaff against the fender liner. I soldered new wire sections in and ran my car through the drive cycle process - I am now ready for everything!

So happy as this stuff was killing me

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