Skip the auto shop - Our mechanics make house calls

Q: Won't drive over 20mph. Reduced engine speed

asked by on

My check engine light came on today. It was driving fine earlier. I went to drive it again and it started to act funny. Almost like it wasn't getting enough gas. Then it said reduced engine speed. Now it doesn't drive over 20mph.

My car has 158000 miles.
My car has an automatic transmission.

Hi There, This may be a sign of a clogged catalytic converter. The catalytic converter converts toxic exhaust gases into less harmful pollutants that are suitable to be expelled into the atmosphere. When this is clogged, this causes these gases to be backed up into the exhaust system not allowing the engine to breathe properly. When this happens, the engine is forced to work much harder to expel these gases. This often results in the engine bogging down, hesitating, shaking and causing very poor fuel economy. This should also cause a check engine light to come on as the O2 sensors should be reading the incorrect amounts of oxygen in the exhaust gases if this is your problem. I would recommend having an expert from YourMechanic come to your location to diagnose and replace your catalytic converter.

Was this answer helpful?

Need advice from certified mechanic? Get help now!

Over 1000 mechanics are ready to answer your question.
The statements expressed above are only for informational purposes and should be independently verified. Please see our terms of service for more details

Get an instant quote for your car

Our certified mechanics come to you ・Backed by 12-month, 12,000-mile guarantee・Fair and transparent pricing

Get a quote

What others are asking

Q: Key won't turn in ignition - please what can I do?

Hello. If the key will not turn in the ignition then either the key is bad or there is a problem with the key lock cylinder. Most of the time, this is caused by a failure in the key lock...

Q: My car makes a weird noise when I first start driving it and also when I put it in reverse but it stops when I start driving

First we must determine what type of noise the vehicle is making. Rattling noises may come from panels whose fasteners have become rusted, worn or broken over time and the panels vibration at low engine speeds, but level out as...

Q: Car overheating during idling or stop and go traffic

Hello. If the engine will stay cool with the AC on or when the vehicle is moving then there is a cooling fan circuit issue. The computer may not be turning on the fan when the engine is getting hot....

Related articles

How Long Does a Distributor O Ring Last?
The distributor is part of the ignition system in your vehicle and its purpose is to route high voltage from the ignition coil to the spark plug. The spark plug then...
Rules of the Road For Iowa Drivers
Driving on the roads requires knowledge of the rules, many of which are based on common sense and courtesy. However, even though you know the rules in...
P2428 OBD-II Trouble Code: Exhaust Gas Temperature Too High Bank 1
P2428 code definition A P2428 trouble code signifies that the PCM has detected a problem in the exhaust gas temperature sensor circuit in bank 1, which subsequently contains the number one...