In 2006 GM apparently issued a special policy adjustment extending the warranty coverage on the catalytic converters on certain models from 80K/8 years to 120K/10 years.

I've got one of the covered models that is exhibiting behavior pretty specific to having a clogged cat and is throwing EGR codes (P0404 and occasionally other P040X codes) but not any cat-specific codes; in any case, I generally clear the codes when they come up so I can tell if it's a recurring problem.  I gather that it's fairly common for the EGR codes can get thrown due to the clogged cat.  The service tech at one of the local dealerships told me on the phone that they won't honor the warranty coverage unless there is an active P0420 (Catalyst System Efficiency Below Threshold - Bank 1) code in the computer.  The SPA says to refer to SI document 657895 for diagnosis information but doesn't mention any specific codes, only the behavior.

Is the tech right that it has to have a P0420 code (only) to be covered?  I know of several other people who got this work done under warranty and have never heard of that requirement.  I know of at least one in particular who also only had an EGR code.

I own a 2003 Chevy Impala. I purchased it new on 12/27/2002.

Recently, it had problems because it was losing vacuum due to a hole burned in the plastic intake manifold.  I took it in on 12/27/2010 for a new intake manifold, and it was determined that the hole in the manifold had been caused by excessive pressure coming through the EGR valve due to a clogged catalytic converter.  Since the intake manifold was collateral damage from the clogged catalytic converter, they replaced both the intake manifold and the catalytic converter at no charge.

I had no idea that it was under warranty when I brought the car in.

I am not sure if this answers your question, but I thought I would share a related experience in case it yielded any useful information.

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Seems like another instance of the code not being required.  And scares me that that could happen from the back pressure and this guy wants me to just drive it around until the magic number comes up.

Intake manifold problems are common with these cars, as GM elected to use a plastic part where they should have used a metal one.

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Haven't had any problems with the manifolds themselves so far (knock on wood) but I had the dreaded LIM gasket failure that's common on the 3.4L engines.  That was a real joy to tear the engine apart and change in the driveway in the wet, single-digit temperatures.

If you are driving along and your RPM suddenly spikes, and your car no longer wants to shift gears, check the intake manifold for burn holes.

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Saw a suggestion online today for someone else who was having similar issues to call the Chevrolet Customer Assistance Center at (800) 630-2438.  From what I gather, they can take some information and arrange a repair at a dealership.  Any ideas if I should do that next or just call another dealership or talk to someone else in the service department?

Any techs confirm or deny the active P0420 requirement?  I've never heard of it at all.  Maybe everyone else is just letting it slide and this guy is a stickler?  Could it be that he's not aware of the clogging issue and the P0420 code is required for warranty repair of a burned-up cat?

im a tech at a gm dealer . if you read the special policy it clearly states under the condition "due to complaints of lack of power or illumination of the Malfunction Indicator Lamp (MIL). " the tech needs to drive it and verify the issue is a plugged cat. converter. If the converter failed its covered under the policy even without the p0420 code.

I called Chevrolet and they verified that no specific code is needed.  I had a hard time understanding him, but it sounded like he was trying to tell me that it did need to have a code though.  I asked him to verify that several times and each time he gave me a different answer.  I think we ended up concluding that no code was required to be in the computer.

He also tried telling me that if I took it in and the cat wasn't plugged up that I would have to pay for the inspection service.  I pointed out that the SPA 05551 clearly states that if an inspection is done and it turns out that the cat isn't plugged and a new cat isn't required that the dealership is to submit a claim for 0.3 hours of labor for the inspection.  He argued and argued and argued with me and we had a pretty heated conversation about whether or not they would pay for the inspection if the cat wasn't the problem despite that the letter they sent to customers as well as the SPA itself both say to take it to a dealership if it's loosing power or if the MIL is on and that it clearly allows reimbursement to the dealer for inspection.  I asked him why the "inspection only" allowance was in the SPA if they didn't cover only the inspection and he told me he didn't know but they sure as hell weren't going to pay for just an inspection if the cat wasn't plugged up.



In any case, I had an appointment with the shop yesterday and went in.  By that point the computer had four codes (two each of P0300 and P0404) which pretty much sealed the deal for me that it was a plugged cat.  The service tech cleared the codes and told me he'd replace it but they had to order the part.  I went in this morning and they swapped it out and now everything is ship-shape and the car's like a rocket ship now.

Thanks to all who replied.

Congrats on your shiny new cat converter!