Loss of Engine Power Due to Plugged Catalytic Converter on Chevrolet Impala

Problem Description and Possible Solution

The catalytic converter may become plugged resulting in loss of engine power. General Motors has extended the catalytic convertor warranty on some models to 10 years or 120,000 miles. Please contact your local GM dealer to see if your vehicle is included.

Problem Data
RepairPal Verified
Average mileage: 121,475 (30,000–200,000)
12 model years affected: 2001, 2002, 2003, 2004, more2005, 2006, 2007, 2008, 2009, 2010, 2012, 2014
95 people reported this problem
Viewing 1 - 20 of 34 comments
I just found this forum, and this problem happened to my car several years ago so I don't remember all of the details. I have a 2003 Impala LS with a 3.8l V-6. When the mileage approached about 75,000 miles, I began to experience a loss of power. Following the directions in a Haynes manual, I checked the ignition coil packs, and any sensor that I was able to test myself and everything checked out okay. I tested the resistance of each fuel injector and they were all within specification. I replaced the air filter, the spark plugs, the spark plug wires, and did other preventive maintenance while I had my tools out. But the loss of power just continued to get worse. After a couple of weeks, I would intermittently get a "check engine" light while I was driving.

I finally took the Impala to a Chevy dealer. I described the problem, and that the vehicle only experienced serious lack of power under heavy acceleration, and asked them to take it for a test drive to fully understand what I was talking about. The mechanic test drove it, and then hooked it up to a diagnostic machine, and didn't come up with any codes and he said that it seemed to run fine. So, I took a mechanic out on a test drive, and put my foot into it, and the lack of power was immediately apparent, however the "check engine" light didn't come on... until I turned around to go back to the shop.

The mechanic hooked the diagnostic machine up to the car again, and this time came up with two codes. Neither provided an obvious cause of the lack of power. So, I let them nickel and dime me, trying this and that, and more than $300 later my car still didn't run properly. I had enough, and left the Chevrolet dealer, and set up an appointment with an independent mechanic.

I explained to the independent mechanic what the car was doing, what I had done to it, and what Chevy had done to it. He said that it sounded like it was the catalytic converter, and that when he was able to get my car in the shop he would loosen the bolts on the exhaust ahead of the converter, separate the exhaust system at this point, and take it out on the highway for a test run.

He called me later that day and said it ran really strong with the exhaust separated ahead of the catalytic converter, thus proving that it was the problem. I had him replace it and have not had a recurring issue with the converter. My Impala now has about 225,000 miles on it.
i have had this problem, engine light would come on and state Loss of engine power. the very time this happen was about 30,000 miles ago. it would happen a few more times but the engine light would always go off the next day. about 5,000 miles ago the engine came on stating loss of power and the light has not gone of since and about once a week i get the "loss of power". my mechanic could not find anything wrong.
what test can be done to test for a bad catalytic converter?
When at stop at a red light my car seems to idle low slightly. When I press on the gas the car hesitates for a while then it will finally go after pressing on the gas harder.
2012 Chevy Impala goes only 20 miles per hour. Engine idles rough. And engine warning light is on. Also says reduce engine power and service stablizer. What might be my problem.
Car revs high and has a rotten egg smell. Loss of engine power especially when passing. Just had transmission worked on under warrantyour and also replaced spark plugs recently. Hoping this is an issue covered under warranty.
Motor ran fine at low rpm. It sputterred & cut out going above 45 mph. When the catalytic converter was changed, it ran like normal.
This happened, was diagnosed as a board, BUT the catalytic converter actually 'plugged up' and blew up through the top of the motor, burning the wiring harness that was laying on top. Chevrolet 'warranted' the catalytic converter and the labor, but will not put a recall on it because they don't want to be responsible for all the problems that it may cause!
They had already ordered the board (think pcm) but it wasn't helping remedy the situation, just as luck would have it there was a mechanic there that had heard of this issue before and sure enough it was all the charred wiring, might not have needed the board, but we had to pay for it anyway. This car really let me down and is the nicest car i ever had and the most i ever paid for one.
I'm sorry but i have NO respect for chevrolet anymore!!!
My 2012 Impala with about 73,000 miles has gone through five catalytic converters all had same systems loss of power. Luckily I am still under warranty. The car is in the shop now. While they were testing it, the convertor actually blew up. What I want to know is chevy going to fix the problem before I go out of warranty.
My 04 loses powere for a 2 to 3 seconds and makes a rattling noise when I push on the gas hard but not to hard.
My chevy Impala is losing power and smells like a rotten egg-I can tell when I push the gas on interstate it doesn't have power like it should I have not had it fixed
Chevy refuses to acknowledge the issue. Car smells terrible while accelerating up a hill. Shifts strange around 30-35 miles to both higher and lower gears. Bonner Chevrolet gave me some nonsense like I was running to high of an octane of gas. They said it didnt throw any codes so nothing is wrong with it. Treated me like I was making it up and didn't take me seriously. Ive had it to Chevy twice now for the issue in addition to a clicking noise in the front, which they changed a motor mount on the brand new car. Very disappointed in a car I'm paying 20k for. I'll never buy another due to their deceptive practices
05 3.8L impala supercharger. At 4000 rpm in neutral starts sputtering choking and dies. Sometimes stalls while driving after accelerating past 30. After 5 minutes or so will start again