What does this mean?

I am about to put my 2000 S-10 up for sale. The last time I got the oil changed I had them run a diagnostic because the check engine light is on. The results were as follows:

1. Secondary Air Injection Malfunction

2. Rear diff service recommended

Is this serious? I don’t know anything about cars other than how to change the wipers and fill it with washer fluid. What does this mean?

The ‘secondary air injection malfunction’ means that a part of your emissions reduction system is not working correctly. The system referenced puts extra air into the exhaust system to burn off unburned hydrocarbons in the catalytic converter while the engine is warming up and running in open loop fuel injection. Is the Check Engine Light ‘on’? Did the service firm pull a Diagnostic Trouble Code and record the number for you, example P0123? Post that and we can help you further.

The recommendation that the rear differential be serviced is not serious. If you have used this S-10 in severe service; have a lot of miles on the truck; or gotten into deep water, you might need the rear differential oil changed.

Hope that helps.

Thanks for the insight. The code is P0410. How serious is this issue? And yes the check engine light is on.

It means that if you live in a state where emissions tests are done, nobody who knows anything about cars is likely to be interested in it, since it would not pass those emissions tests. And, that issue is like a “pig in a poke” so to speak, since the prospective owner would not necessarily know how much it would cost to make the truck emissions-compliant.

Additionally, prospective buyers will have legitimate concerns about how this vehicle was maintained, overall. Having an illuminated CEL is a pretty good way to repel buyers.

Well I am in Nebraska and we do not have to have our vehicles inspected yearly like we do in my home state of Texas. Is that what you are talking about?

This is not a serious code. My research brings up the same definition for the P0410 DTC so a mechanic will have to trouble shoot the system. It could be a faulty solenoid or air switching valve. I am sure that GM has a troubleshooting chart for this system.

Good luck on this.

I always tell people that if the CEL is on that they should not buy the car. A lost sale will never come back. Don’t lose yours.

So how much are we talking about in repairs here?

Even if you don’t have annual inspections in Nebraska, the state might require an inspection when a vehicle is sold. You might want to check into that detail.
However, even if no inspection is required, everybody whom I know would instinctively walk away from a car with an illuminated CEL.

I have a 2001 S-10 with the same problem (Secondary air malfunction). There is a pump below the radiator that performs the function that Researcher describes. If you’re a DIYer, and if your state doesn’t have strict clean air regulations, I can tell you how to “fix” that problem. Or you can do the same repair that your local shop will do to fix it, however any drive through a large puddle will cause it to come back on.

If its not too complicated I would like to do it myself. But I am not the handiest when it comes to cars. So what is your solution?

and this wouldn’t have anything to do with my a/c not blowing cool air when it is hot out would it?

Yes. The “problem” is meaningless in Nebraska. It does not effect performance or drivability. Reset the light and sell it.

Find a mechanic and get a quote. If it is too high for you, be sure to mention to the prospective buyer. You’ll probably lose a couple of interested people, but someone will give you an offer.

No. Totally different system.

So how do I reset the light or does a mechanic have to do that for me?

Sorry this is so long.

It can be difficult if you don’t have the right tools. The “fix” involves removing the “smog pump” located below the radiator and all of it’s associated plumbing. This also means that you will have to remove, cut, heat and bend the pipes that connect the pump to the exhaust manifold. You will also have to “bag” the quick disconnect plug that sends power (and the CEL signal)to the pump, then stow it out of the way. And finally, you need to disconnect and cap the vaccume line that attaches to pump. After the work is done, resetting the CEL light can be done by disconnecting the battery, wait a little while and reconnect it.

If this sound too difficult, then take it to a shop. They will more than likely remove the pump, drain the water out of it (this is what may have caused the CEL to come on) and reinstall it. Then they will check the vac lines for an open. You can check for this yourself. The vaccume line stretches from the right side of the engine (when viewing from the front), over the back and top of the engine, then down to the pump under the radiator. It’s very posssible this line has a hole in it.
Hope this helps.

Be careful about removing the secondary air system pump. You have an electrically driven air pump and switching valve on the 2000 S-10. Even if you remove the system, your OBD11 ECM will recognize the nonoperation of the system and reset the code P0410. Also if you try to register this truck in an I/M State, the removed system will have to be reinstalled and made to work before the truck will pass inspection. The Federal emissions laws are very strict on modification of the emissions system so reference your states compliance agreement before you go messing with the emissions systems on your truck.

Your secondary air system has a ‘AIR electronic module’ over on the right fender near the battery that feeds electricity to the pump. There is a relay that is activated by the ECM and two fuses that pass power to the pump motor and the switching solenoid so have your mechanic check that out. The AIR motor and pump is mounted low behind the radiator as ccooper noted. There is a TSB that describes the ingestion of water causing stoppage due to freezing and corrosion. The cost for the pump is approximately $250 with 0.9 hours of shop time for replacement. Have the mechanic reference the TSB when you take this in for service.

Hope this helps.

You can reset the light by disconnecting the battery for a few seconds…

Researcher has the best advice: correct the problem the right way. My truck has the horrible fate of being “mine”. Therefore the wheels will literally have to fall off before I think about retiring it. And even then, I’ll find a way to put them on for one more mile. As far as the trouble code/CEL for the pump, it’s been about a month and no light. Hopefully, it wont come back, but I’ll keep your advise in case it does.