Blogs Car Info Our Show Deals Mechanics Files Vehicle Donation

Post oil change catalytic converter failure

Took car in what seemed fine working order for an oil change. The next day the check engine code began to flash and the engine began to run rough. Went back to the dealer and they said the catalytic converter needed replacing. Seems like a mighty coincidence! If the dealer over filled the oil, how long would it take to flood the converter and ruin it? Could this have happened in one day? How could I prove it? Left the car at the dealer since was on the way out of state. I told them not to work on the car since, but am worried that if they know I’m on to them, they may drain the excess oil, before I can get the car and get a second opinion. Advice?

Where was the reading on the dipstick when you checked it?

1 Like

Did you check tho oil level? It isn’t clear from the post. also, what year I said your Fit and how many miles on it? It is possible tho catalytic converter is covered by warranty. Since the issue started shortly after the oil change they performed, they would clearly be responsible for the oil level. If you produce a receipt, that should be enough evidence.

It’s 2007 Fit, with 122,000 miles on it. It’s passed its extended warranty by 1000 miles. I didn’t check the receipt or dip stick yet, as I had to leave the car and quickly get a rental to drive out of state to get to Thanksgiving. I told the dealer not to touch the car and I will pick it up tomorrow to check oil and receipt and take for a second opinion elsewhere.

t’s 2007 Fit, with 122,000 miles on it. It’s passed its extended warranty by 1000 miles. I didn’t check the receipt or dip stick yet, as I had to leave the car and quickly get a rental to drive out of state to get to Thanksgiving. I told the dealer not to touch the car and I will pick it up tomorrow to check oil and receipt and take for a second opinion elsewhere.

So without checking a single thing, you seem pretty sure the dealer is somehow responsible . . .

A flashing check engine light means a severe misfire, bad enough to damage the catalytic converter

Has your vehicle been running well, BEFORE the oil oil change?

Considering your mileage, I hope you don’t still have the original spark plugs . . .

Yes, the car was running perfectly before the oil change and the spark plugs were new when I bought from the dealer at 94,000 miles. I’m not making any assumptions, just trying to do my research on the subject.

I was thinking about the federal emissions warranty, but that runs for the first 8 years or 80,000 miles, whichever comes first. That expired long ago by mileage.

Someone needs to look at the car to figure out what is wrong. If you expect the dealer to repair something that they did wrong, they need to evaluate it. DoD the dealer tell your u want codes were read from the Car? If so, please post them. If not, get the codes and post them. The dealer must have read them because they offered to change the catalytic converter. If they have not read the codes yet, there is no reason to offer any solutions.

Thanks for your advice! The dealer plugged their code machine into to car and supposedly read me the results. I did ask them why they weren’t evaluating what caused the failure, as I read that if you don’t find the cause, the problem will just repeat itself. They seemed decidedly uninterested in finding an outside cause, which renders me even more suspicious.

I will ask for the read outs when I pick up the car tomorrow.

I don’t see a connection between an oil change and a catalytic converter problem. Also a catalytic converter issue should not give you a flashing check engine light (CEL). If the code was related to the cat, the light would be solid. A flashing light means that something else is wrong and it will damage the cat if not fixed ASAP.

This could be a total coincidence or it could be that the oil change tech may have somehow damaged or disconnected one of your spark plug wires when adding the oil.

If he forgot to drain the old oil out before adding the new oil, then the engine could be way overfilled and that could cause a plug to foul. Worse case, he could have drained the transmission instead of the engine and now your tranny is 2.5 qts low. Not sure if the transmission will work that low, but it might. If its a manual, it will work for a little while.

Now, sorry to be a little critical, but you should have opened the hood at the first sign of trouble and looked for yourself, including checking the oil level, before taking it to the dealer.

BTW, other things he could have done, knocked off a vacuum hose, damaged a wire to the MAF sensor etc.

Thanks Keith,
This is interesting! Yes, I do feel a bit stupid for not looking myself. I had my 82 year old mother in the car and was feeling a bit panicked for time, and was near the dealer at the time of the incident on my way from Maine to CT. I left the car at the dealer and rented a car to get going ASAP. I’ve been kicking myself ever since. I am making my way back today to pick the car up, to take a look myself and then get a second opinion. I will check all you ideas at that time. Grateful for your suggestions !

Sent from my iPhone

For what it’s worth… if you do decide to proceed with getting the catalytic converter replaced… please look for options outside of the dealer’s service department, like a local muffler shop. Dealers will SHOCK you with the cost of replacing the CC with an OEM model. My brother nearly junked his car once because the dealer wanted to charge him like $1500 to replace the CC on his car. Based on the advice from this board, I sent him to a muffler shop, where he got it done for…$300.

This past Thursday I found out about another family member who recently gave $2000 to the Chevrolet dealer for a new CC on his 2003 Chevy truck. I had to restrain my shock for him, as I knew he could’ve have saved about 3/4 of that cost…as well as that probably being about what the truck is worth, or more.

Anyway… shop around for CC replacement prices. Don’t just take the dealer’s offer. Good luck.

I will add a few things . . .

Those cheap catalytic converters that are being mentioned aren’t very high quality

Yes, they’re effective enough to get rid of the code . . . IF the catalytic converter truly was the problem

However, they are very cheaply constructed, versus the factory part, and don’t expect them to last as long . . . time and/or mileage . . . as the original. Factory cats are required to last a certain amount of time. This may no longer be entirely accurate, but aftermarket cats aren’t held to the same high standards. Not even close

So, for example, if a factory cat lasted 10 years and 250K, don’t expect a cheapo cat to last that long. This might be important for people such as George and others on this forum, who like to keep cars a very long time

But if you only want to keep the car for another 3 years, or are planning to flip it tomorrow, then a cheapo cat may be the right answer

1 Like

I had the same problem. However with additional layers. This is how my nightmare went:
Coolant leak/ recall revive performed
Water pump/serpentine belt replacement
Several warning light on dash related to braking system
Service maintenance (cost of $2,100)
Engine light /steering vibration/rough idling/engine noise
Catalytic converter replacement
Engine noise/rough idling still
NOW I’m being told that noise is coming from supercharger / timing (or tension) belt replacement/ bearing replacement. Tear down per dealership will need to be performed to further diagnose etc resulting in a estimate of $10,000-$14,000 cost.

Car still under warranty ad those parts are covered however they have created a loop hole to void warranty coverage. I have had every service at every interval performed on my car. All done at same place. Same dealership.
Rangerover sport 79,000 miles on it.

What does any of that RangeRover crap have to do with a Honda Fit?


Do you have a point other than:

  1. Purchasing a Range Rover is a bad idea.


B. Purchasing supercharged Range Rover is a very bad idea…