Marlenia

My second Mercedes, don't want to drive anything else!
CODES P0432 P0422 P0400m P0141, P0161 - Car has 257,00 miles, and kept serviced by MB. Guidance to parts, labor, - currently starting and running well. Except for the CHECK ENGINE LIGHT that is on, with the associated codes I am told.

Thanks in advance for any guidance.

PelicanParts.com

Welcome to MBWorld! Try posting your issues in the W208 section of the forum here. Good luck!

dbldpr

Welcome and good luck

MJ50

moved to W208 forum...

MarcusF

The codes seem to point to the catalyst material no longer performing as it should and the O2 sensor heating element and/or wire being dead. The cats may or may not be worn out, but a smog test (a sniffer test to be specific) will tell you whether the cats are actually working. If the cats are working within reason, the secondary O2 sensors are shot. If they're original equipment O2 sensors, they may have been shot 6 years ago. The primaries too.

It is possible for you to install new secondary O2 sensors and get the same results. That because when new, the CLK430 was an ULEV (ultra low emissions vehicle). It may no longer be ultra low, but still low enough to pass smog. The ECU expects the exhaust oxygen content to be a certain level. That level is confirmed by the secondary O2 sensors, and if it's not, it triggers a code. It wouldn't surprise me if the recommended fix in many places was new cats and new O2 sensors. Figure at least $2K for OE cats and another $1K in OE sensors, plus installation. Although a pre-2001 model year car may have less expensive O2 sensors and only cost $750

There is an alternative, and very few shops will do what I'm going to suggest. I can 100% guarantee a dealer will not. If you pass the sniffer, the car produces reasonable smog levels. [caution: very long sentence alert] In that case, screwing spark plug non-foulers into the O2 sensor bung, and then screwing the O2 sensors into the non-foulers will move the O2 sensors far enough out of the exhaust stream, that your accursed failure code will cease. Dorman non-foulers are about $5 per pack on Amazon and you'll need two. The nose will have to be drilled, to open them up a bit. Once the car is on the rack, it's a 15 minute job, provided the exhaust isn't so hot that it's causing the polar ice caps to melt. $10 in parts, $5 to drill them, another $25 in labor and a $100 tip IF someone is willing to do it. If you're handy or know someone who is, $20.

jonUF02

What is your location? I have a full 430 exhaust with 02 sensors, probably has half the mileage of your car. I replaced it with a 60K mi used exhaust system when the dealer told me I needed to replace the whole system to get rid of my rough idle issue. Replacing the exhaust system made no change, and the problem ended up completely unrelated to the exhaust or sensors. I'm in Orlando, FL, and I would rather not attempt to ship. I'll give you a very good price.