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sprinkles08, ASE Certified Technician
Category: Mercedes
Satisfied Customers: 22803
Experience:  ASE Master and Advanced level certified. Factory trained with 15 years dealership experience
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I failed the emissions test. The codes read PO432-PO422...My

Customer Question

I failed the emissions test. The codes read PO432-PO422...My car doesn't ride as smooth as it use too. Can you help with a solution?
JA: Just to clarify, what's the exact code? And have you tried to reset it?
Customer: The code are P.0432-P0422...No I have not done anything? I'm trying to find out what's wrong with it? It's also running slower then the norm.
JA: What is the make/model/year of your car?
Customer: 2004 .CLK 320 MERCEDES
JA: Are you fixing your vehicle yourself? What have you tried so far?
Customer: No. I'm trying to see if I can find someone to tell me why it's running so slow and what the codes really mean? The guy at the emissions place says it's my catalyst converter.
JA: Anything else you want the mechanic to know before I connect you?
Customer: No...Thank you for the help.
Submitted: 10 months ago.
Category: Mercedes
Expert:  sprinkles08 replied 10 months ago.

Hello and welcome to JustAnswer!

These codes are indeed for catalytic converter efficiency. The switch rates of the up and downstream oxygen sensors are compared and if it sees the switch rate of the upstream sensor cross a threshold in relation to the downstream sensor then an efficiency failure code will set.

There are just a couple things that will set these codes. An exhaust leak can draw oxygen into the exhaust stream and set them, as will lazy upstream oxygen sensors. The most likely cause would be the converters themselves.

Customer: replied 10 months ago.
Thank you. I put it in the shop this morning to see if it's the catalyst converter. The mechanic said it was because the way my car is running. He's checking it out now... Thanks again.
Expert:  sprinkles08 replied 10 months ago.

You're welcome!