Service Engine light = Air Pump issues

[guitarfish]

My Service Engine Soon light is on in my '02 Grand Prix GT. I took it to an AutoZone, they scanned it and said "it's getting too much air" and couldn't offer much else. I took it to a reputable shop, they spent a few hours on it and said it seems to be the air pump.

More specifically, they said it could be the air pump, the air pump valve, or the valve solenoid. The three components tally up to about $400 (not including labor). The shop called a Pontiac dealer, the dealer said, "yeah, we sell alot of those air pumps."

I was told I could replace the solenoid & valve ($200) first, that might fix the issue, but I might have to replace the pump too (for another $200). Incidentally, I've got 142,000 miles.

SO, anyone else have this issue? Not happy about it of course, that's a lot of $$$. What a PITA.

[BNaylor]

Depending on the odb-ii DTC error code you should post the code(s) before wasting money. Alot of things can cause a secondary air pump emissions related problem.

[guitarfish]

My code is: "P0410 Secondary Air Injection System Malfunction".

I found a place to look them up: OBD-II Trouble Codes

[richtazz]

It is fairly common to get water in the air pump, which causes it to fail. It is mounted in the driver's side fenderwell area. Since you live in Pennsylvania, and the air reaction pump is catagorized as "California emissions only", I assume your area has stricter emissions regulations than the federal mandate. Double check your Service Parts Identification label (located on the underside of the trunk lid) for the code NC8, which denotes the car having the "California emissions" equipment. If the above code isn't there, your car will not have an air pump.

[guitarfish]

I'll give that a look. I purchased the car from a dealer just over the border in NY, and I remember something on the window sticker about NY emissions, maybe that's why. Where I live in PA they don't even test emissions at inspection time.

I have a 98 Grand Prix GT also, bought in PA, I don't even know if it has an air pump. So let's assume for a minute the AP isn't needed...how does one disconnect it such that the OBD computer ignores it? If the pump isn't connected, then it can't report a failure code, so the computer doesn't light the Svc Eng light? Something like that?

[richtazz]

Disconnecting it will not make the PCM ignore it. It could trip multiple codes related to the air pump and it's related circuits.

[BNaylor]

There is no doubt in my mind he has a green state Grand prix. Non NC8 cars will not trip a P0410 DTC error code.

Mechanics will typically replace all air injection system parts like the pump, however, that may not resolve the issue. $$$ items.

Check into the possibility of a flaky CAT convertor or 02 sensor before the CAT. You may get a free CAT convertor because GM delivered GPs in 2001 - 2002 with flaky ones.

The generic odb-ii codes you have do not tell you enough or how to fix the problem. Basically you have an air injection system malfunction meaning diagnostics has detected an air pump that is not flowing amount of air into the exhaust system. Although the pump could be flaky it does not mean the air pump itself is bad.

Two tests are run by the PCM. Non-intrusive and Intrusive.

The non-intrusive test is run at startup in open loop mode. It looks for 02 sensor voltage above 598.96 millivolts for a rich time ratio of 1 but is failing. To pass the 02 sensor voltage must be below 0 mvolts for a lean tme ratio of 1. Therefore, to fail the 02 sensor voltage is below 598.96 mvolts for a minimum of 5 seconds after the pump is turned off. Must have above 598 mvolts for 25 samples to pass.

In the intrusive test the air pump is turned on to force a change in the 02 sensor signal. The 02 sensor signal must be forced continuously below 73.785 mvolts for greater than 1.5 seconds to pass.

GM has a TSB out covering a mod where a plastic shield is added because the air pump was accumulating water. But I've seen this done and the P0410 issue not resolved.

[guitarfish]

Thanks for the replies guys. Here's where I am: I checked the window sticker - it's a ULEV car, for MA/VT/NY/CT. My 98 GP is not, and there's no air pump junk under the hood.

The shop tech reset the Svc Engine light for me twice. Each time I got about 40 miles before it came back on, so I'm guessing it failed the intrusive test.

I found a 30amp fuse that simply says "AIR". I yanked it. The car starts fine, of course the Svc Eng. light is still on. Honestly, I didn't expect pulling this fuse to accomplish much.

So, how would someone disconnect an air pump, such that the on board computer doesn't look for it?

[BNaylor]

Its complex. The only way I know of to do it right is to have the PCM module reprogrammed to inhibit the air pump and all test routines associated with it. You can remove it and block off the plumbing to the exhaust but undoubtedly the DTC error code would set to include an annoying SES/CEL light.

I don't think there is an easy solution.

[guitarfish]

Thanks for the feedback. Someone remind me to NEVER buy a car in NY state again. I could really kick myself. My wife's 98 Grand Prix has 235,000. NO AIR PUMP, NO SVC ENGINE LIGHT!!