Mercedes-Benz Catalytic Converter Split and Oxygen Sensor Code.

Recently, I had a check engine light for the O2 sensor on a Mercedes-Benz. The car also sounded like it had an exhaust leak.
After getting the car up on the lift, I discovered that the catalytic converter was separated. I received a couple of quotes, one for an aftermarket part that cost $1400. The other option was to cut and fit a universal catalytic converter for $300-$400.

Before spending $$$, I decided to remove the whole catalytic converter. The ceramic substrate was still intact, so I thought, why not fix the existing one? Welding the old catalytic converter fixed the exhaust leak and the O2 code.

Here is a picture of the catalytic converter split in half.

 

The ceramic structure was still intact. If the ceramic substrate is cracked, melted, or missing, there is no point in trying to weld it back together. You would get a check engine light, and it is illegal to drive with a damaged catalytic converter. Do not remove, bypass, or disable the catalytic converter. Any repair must leave the emissions system fully functional and comply with federal and state requirements.

 

Here is the converter after welding. This was only my second time welding, so don’t be too harsh on me.

 

After sealing the exhaust leak, I cleared the fault code and completed a drive cycle to confirm that the code did not return.

Troubleshooting Faulty Oxygen Sensor

Before replacing an oxygen sensor or catalytic converter, use the UCAN-II Pro to read the exact fault code and compare the upstream and downstream oxygen sensor live data. Full AI Diagnosis can help determine whether the problem points to an exhaust leak, sensor fault, or converter efficiency issue. It supports more than 140 makes, 3,500 active tests, and 1,000 special functions. It also includes built in TPMS sensor programming, a rear VIN scanning camera, no subscription, and no AutoAuth requirement.