I suddenly noticed a noise coming from the engine that sounded like a noisy lifter and stopped using the car after hearing it. The next day I called the dealership to check and verify if they could check the car and do any work required under the CPO Warranty since they were a Chevrolet Dealership and my vehicle was a GMC Yukon XL Denali but they were the closest GM Dealership to me.

They advised that they could since they were part of the GM Family and could do any work required under the CPO Warranty.

I then arranged to have the car towed to the dealer via my AAA Membership.

On October 20th, 2025, I had my 2019 GMC Yukon XL towed in for inspection and repair under the GMC Certified Pre-Owned (CPO) Warranty, which was due to expire on October 27th, 2025.

The dealership advised that the vehicle would need to be examined by one of only 3 qualified mechanics in their shop who could do this evaluation and determination if the issue(s) were covered under the CPO Warranty and it would be about 3 days before they could have one of their 3 qualified technicians check the car.

The Service Adviser called me back on October 22nd, 2025, and advised that Cylinder 5 had noisy lifters and that they would be changing out the engine with a newly rebuilt engine, all under the CPO Warranty. The Technician who performed the original evaluation and replacement work was XXX (APQ), as per the repair invoice but the Service Adviser said it would take 3-5 days to get the replacement engine in and then about 2-3 days to replace the engine.

The Service Adviser mentioned a few other items that might need work but were not related to the reason I had called and had my vehicle towed in.

I opted to have some of that work done, at my expense, which included replacing all of the items that needed to be removed to change out the engine but normally would have been re-installed on the new engine, this included the following: • all the hoses (coolant and heating) • belts • starter • spark plugs • spark plug wires They also had asked about servicing the transmission, which I opted to have done as well, again at my cost. Which included a new filter and fluid change and inspection.

However, less than 24 hours after receiving my vehicle back, the check engine light came on, and I called the dealership immediately. It was a Saturday and the Service Adviser was not on or unavailable and they closed at 3. I called back on Monday, and they told me it was probably something minor that needed to be reset. Then I received a call back from and he said it was the catalytic converter, and it was going to cost about $6000, and they were only going to offer to cover 30% of the cost. I told him I’d have to review my options and the CPO as this should have been covered under the CPO as it was due to the engine failure. After that call, I asked if it was safe to drive the vehicle and not cause any damage to the new engine and he said yes but the check engine would remain on. I picked up my car and then decided to call GMC back. The original person I spoke to at GM was not available and I was transferred to someone else who essentially repeated what the Service Adviser had stated, I asked to have the original person I spoke to call me back, which she did but essentially said the same thing and she stated that the vehicle wasn’t covered anymore, that that part of the CPO had expired, but it expired while at their shop: 1) waiting to be examined and checked out by a qualified technician at their dealership, 2) then waiting for a new engine to come in, 3) waiting for it to be replaced; once it was replaced and picked up, the check engine light came on less than 24 hours later. The underlying issues and why this should have been replaced at the same time as the engine are fairly clear based on the results documented by their own technician: 1. They started the vehicle and verified noise coming from Bank 1 of the engine. 2. They removed the valve cover and inspected the pushrods and found them all able to be moved. 3. Inspected individual cylinders on Bank 1with a stethoscope and found tapping coming from cylinder 5. 4. Removed cylinder 5 rocker arm and pushrod and noise was still present. 5. Removed Bank 1 cylinder head and lifters and found cylinder 5 lifter stuck in the cylinder and the cylinder scratched and damaged. 6. Replaced the engine assembly and all 1 time use components and seals. 7. Evacuated and recharged R1234YF A/C system. 8. During the transfer of parts, the left engine mount was broken and had to be replaced as well. 9. Refilled the new engine with oil and coolant. 10. Test drove the vehicle when work was completed to verify the repair.

Details of the Repair Issues • The vehicle was at the dealers for 2-3 days before they could have a qualified technician inspect the vehicle. • Upon inspection and tear down, the technician determined that cylinder 5 was bad and that the engine should be replaced. • The Service Adviser said it could take up to a week to get the new engine in, then it could be 2-3 days to change out the engine. • I was called on Oct 31 and told the car would be ready that afternoon. • I picked up the car around 3:50 PM on Friday, October 31st. • The check engine light came on Saturday, November 1st around 2 PM. I called the dealer at 2:07 PM and asked to speak to my Service Adviser, Raul. I was told he wasn’t in and that Service would be closing at 3 PM. • I called back on Monday at 9:06 AM to talk to the Service Adviser, left a message and he called back at 9:54 AM. • I brought my car back in to be checked and after they checked it out, they said the catalytic converter was bad and needed to be replaced. The Service Adviser said it would cost about $6000 and they only offered to cover 30 percent of the cost but never provided a written estimate, which I asked for multiple times and NEVER received. • I then had an independent mechanic run a scan and asked for the results of the scan. The scan will be attached. Some bullet items regarding the initial engine trouble and the scan data for the catalytic converters are below: 1. The engine was replaced under the CPO because of extensive damage to cylinder 5 on Bank 1 of the engine. The lifter was stuck in the cylinder and the cylinder wall scratched and damaged. This is all data documented in the original analysis and on the repair invoice from Circle Chevrolet. With that kind of engine damage, the catalytic converter assembly should have been changed out. 2. The catalytic scan data clearly shows the problem is with the catalytic converter for the Bank 1 cylinders and cylinder 5 is a Bank 1 cylinder. 3. The dealer had my vehicle from October 20th through October 31st. GMC was saying it wasn’t covered under the CPO Warranty because it was after October 27th. That is outside of my control when the vehicle is at an authorized dealership and waiting on them to even look at the car and then wait to get the parts in to repair it and then the time to repair it. Then to say less than a day after completing the engine replacement that they’re not covering the catalytic converter replacement. 4. Also, for work of this magnitude and knowing the type of engine damage that was present, they should have known that the catalytic converter probably needed replacement. From the technicians’ notes, it was taken for a test drive of approximately 6-7 miles and only one test drive. My understanding is that the check engine light for these types of issues usually requires at least two cold test drives as the first one may indicate a high number but will wait for a second reading before setting the Check Engine light. 5. This vehicle has a welded Y pipe with a separate catalytic converter for each side of the engine. You cannot change just one side; you have to change the complete Y pipe.

• After they only offered to cover 30 percent of the repair and did not provide a written estimate, I called GMC back and they said it was because it was after the CPO expired. I mentioned to the lady I was talking to, does that mean I need to contact an attorney to get this resolved? She just said if I do that, they won’t talk to me. • I then placed 3 separate calls to the Service Adviser and asked him to please provide a written estimate to replace the catalytic converters. He never returned any of my calls. • Then I called the Service Manager, and spoke to him. He initially seemed like he wanted to try to resolve this before I started writing letters, etc., and he asked me to give him a few days to see what he could do. I waited and waited and then called him back 3 or 5 times and asked for a status update, nothing, crickets, no return phone calls. • At this point, I’m ready to proceed and review my options, including small claims court, if necessary.

Attempts to Resolve the Issue I have made several attempts to resolve this matter directly with the dealership, including: • Communicating with their service department both in person and via phone. • Requesting written itemized estimate to replace the catalytic converter. • The catalytic converter failure for that side of the engine is directly related to the cylinder 5 issues and this is totally obvious and visible when examining the data pulled from monitors attached and the data charted for both Bank 1 and Bank 2. This car has a welded Y pipe with a catalytic converter for each Bank on the engine. The data clearly shows the issue with the catalytic converter for Bank 1, which is the bank where cylinder 5 is located. • Asking that the full cost to replace the catalytic converters be covered (all parts, materials, and labor) under the CPO as this should have been done due to the results of the engine tear down and cause for the engine replacement and the fact that the vehicle was sitting at the dealership waiting for them to inspect and determine the original problem and then waiting for a replacement engine to be delivered and then installed.