Air pump failing, grumbly engine and O2 sensor

gradstudentanna · Post by **gradstudentanna** » 10 Feb 2010, 23:45

Hello,
The secondary air pump on my 1996 Volvo 850 is failing. It makes this awful screechy sound when it's on. I took it in to a reliable Volvo mechanic to get the sound diagnosed, and he said that the air pump below the battery was failing, that I could unplug it, and that I should be able to drive fine without it.

First off, how important is it to replace this part? Can I pass emissions without it? I'm not due for another test for two more years.

Lately, my engine has started making a low grumbly rattle. It started when the Check Engine light came on while on the freeway a couple weeks ago. The mechanic said that the code could be a couple things, but it had something to do with an O2 sensor that was likely failing, and that he'd need to check it out further. Is the grumbly noise connected with the O2 sensor? What is the most cost-effective way to fix this?

Thanks a lot.
-- Anna

gradstudentanna · Post by **gradstudentanna** » 10 Feb 2010, 23:50

Nearly forgot -- my 850 has about 186,000 miles on it. Trying to break that 200,000 mark!

Post by **jblackburn** » 11 Feb 2010, 07:43

The air pump is not important to the car running, but it will keep it from passing inspection, and it will keep the check engine light on.

The grumbling? I'd think an idler pulley or something hooked into the serpentine belt. But if you can take a video of the noise for us we'd be able to be a lot more help with that one

I'm hoping mine will hit 200,000 before having to go through any more major repairs, but at the rate things have been going...

Brewmaster · Post by **Brewmaster** » 11 Feb 2010, 09:14

Question - the air pump is designed to run only in the first few minutes of a cold start, right? So *in theory* if we were to clear the CEL, show up for emissions test with the car all nice and toasty, we should be able to pass, possibly, right?

(I have to have this thing tested by the 17th and I don't have the cash to front a new pump yet)

Post by **jblackburn** » 11 Feb 2010, 09:32

Question - the air pump is designed to run only in the first few minutes of a cold start, right? So *in theory* if we were to clear the CEL, show up for emissions test with the car all nice and toasty, we should be able to pass, possibly, right?

Yep! Reset it, get the car warmed up, and then run like hell to the inspection station and pass it.

My car, in all its infinite wisdom, triggered the CEL as they were DOING the test, so it failed. It couldn't have just waited 5 minutes.

Brewmaster · Post by **Brewmaster** » 11 Feb 2010, 09:40

Oh dang, that's crap luck there

Last time I had mine reset, it took 4 days of driving 60+mi before it came back on

Post by **IVIUSTANG** » 11 Feb 2010, 12:05

I believe the P0410 code will be a pending code and they will fail a car for that. The only way to beat it in the short term is to start your car and get it good and hot; then shut it off reset any codes, restart the car and let it have enough driving cycles in this manner so as that it is not a pending code any longer. Then immediately take it to be inspected. The key here is to never have even close to a cold start once that code is cleared. A cheap OBDII reader should tell you if you are pending, my $30 tool even tells me what "emissions" systems are in a not ready state, which will fail you. I am so lucky I live in a region where there is no emission standards

- Jesse

Post by **jblackburn** » 11 Feb 2010, 12:19

It also comes on if you idle for extended periods of time. I decided to go get something to eat and sat in a drive thru right before I took it to get inspected, heard the air pump start up, and thought "oh no". I'm not really sure what triggers the code exactly...my pump still worked, I just think it had problems getting started.

gradstudentanna · Post by **gradstudentanna** » 15 Feb 2010, 21:16

Thanks for all the help.

My dad disconnected what he thought was the secondary air pump below the battery. Weird thing is that it's still making the squeaky noise when it starts up -- although it seems to be quieter than it was before disconnecting the air pump. The car sounds a lot less "grumbly," though, and seems to be running a lot better. Dad wants to reconnect the air pump, since apparently that's not what is causing the noise.

We put a rebuilt ABS module in (mine was failing -- seems to be a common problem with this Volvo model). The Check Engine light, which the mechanic said was on due to a faulty O2 sensor, is now off. I've been driving the car around for the past couple of days, and the light hasn't come back on.

Should I even worry about the squeaky noise anymore? I could take it back to the mechanic to get it checked out again. But if no lights are lighting up on my dashboard, then it's not a problem, right?

Thanks,
Anna

Post by **jblackburn** » 15 Feb 2010, 21:43

Chances are the check engine light will turn back on when the car says "Hey, what the heck! That air pump isn't working when I tell it to!" It takes a few repetitions of a code to trigger the light to come on again. Mine would take a few days - 2 weeks sometimes without a code. I'm surprised unplugging it didn't trigger it right away though.

BUT the O2 code is likely related to that air pump not working when the engine is cold (did you happen to know which sensor it is? Front or rear?)

The good news is that you can probably ignore both of them without worries for now until you are able to repair the air pump to pass inspection. The bad news is the inspection (depending on when you have to have it done of course)...even if you don't have a check engine light on, it won't pass if the emissions system is in a "not ready" state (for codes that are pending but haven't turned on the light yet).

As far as the "grumbly" noise, that wouldn't have anything to do with a sensor. Are either of the noises you describe by chance coming from the passenger side of the car near the belt area?