Q: My car failed the smog test and two codes came up: P0422 and P0432 Both Catalyst 2 Efficiency Below Threshold Bank 1 and Bank 2.

asked by on

Can the catalytic converters be repaired or do they have to be replaced? How much would it cost? Who can make the repair other than the dealer? I am worried the cost is more than what the car is worth.

My car has 249000 miles.
My car has an automatic transmission.

Hello there, thank you for asking about your 2003 Mercedes-Benz ML350.

The catalytic converters have to be replaced. You have 4 options for parts and labor: 1. Have a certified technician from YourMechanic come to your home or office to replace your catalytic converter. This service includes both parts and labor. 2. Buy the parts from Mercedes-Benz. This will include a length of pipe, for the left and the right, that have 2 converters each. Have Mercedes-Benz give you a quote for the whole job. You could also buy Mercedes parts and call around shops to get a quote for installation. 3. Aftermarket replacements are available to buy that are specific to your car and will be less expensive than the parts form Mercedes-Benz. You can call local auto shops to get a quote for installation. 4. Have a muffler shop cut out the old converters and weld in new ones.

If you choose to go to an auto repair shop, find one that specializes in German cars. You can also have a technician from YourMechanic who is specialized in German cars come make the replacement.

Was this answer helpful?

Need advice from certified mechanic? Get help now!

Over 1,000 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

Ask a Mechanic
(100% Free)

Have a car question? Get free advice from our top-rated mechanics.

Ask A Mechanic
Over 10,000 questions answered!
  1. Home
  2. Questions
  3. My car failed the smog test and two codes came up: P0422 and P0432 Both Catalyst 2 Efficiency Below Threshold Bank 1 and Bank 2.

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: If still runs great do I need new spark plugs yet?

Hello. The factory Mercedes recommended service interval for the spark plugs to be changed is actually at 60,000 miles or 6 years - whichever comes first. As for the price, you may already know that the dealers typically charge substantially...

Q: Reduced Power light

Hello. It is possible that the catalytic converter is clogged causing a lack of power in the car. It is possible that cleaning out the catalytic converter will fix the problem, but most of the time the catalytic converter needs...

Q: Engine whines, knocks, and has slow acceleration

Hey there. I would suggest you have a mechanic come and listen to the noise and verify the noise you hear. The engine may be making normal noises. You may be hearing the idle control and air pump noises that...

Related articles

What Causes Hoses to Leak?
While the largest part of your engine is mechanical, hydraulics plays a significant role. You’ll find fluids at work in a number of different areas. Your car's fluids include: Engine oil Transmission...
How Long Does a Heater Control Valve Last?
Keeping the right amount of coolant in a car is essential in keeping the engine at the right temperature. Failing to have the right amount of coolant or even bad elements...
P0052 OBD-II Trouble Code: HO2S Heater Control Circuit High (Bank 2 Sensor 1)
P0052 code definition HO2S Heater Control Circuit High (Bank 2 Sensor 1) What the...