[lilfoot]

I was driving home from work and a Drivetrain Malfunction error occurred while climbing a long hill. I checked under the hood and the exhaust was glowing red from the turbo down to the catalytic converter (not normal). I was able to drive home and let the car sit for a few hours to cool down, and did another test drive which also resulted in glowing exhaust.

I checked for codes using ISTA and it showed low boost pressure codes but car still drove fine and turbo sounded like it was spooling.

I dropped the car off at BMW and they performed a test plan on the turbo, checked the PWG and verified all good, then did a smoke test for leaks and inspection of the catalytic converter. No faults found with the basics, and they wanted $600 to pull the cat to check the turbo. I declined and took the car home to do it myself.

My inspection of the turbo shows excess play with the wastegate which is apparently a known issue in other bmw turbos from previous years. I did have some excess rattle noise but I assumed it was the direct injection this whole time. My car has 122k miles so I went ahead and bought the MHI N20 big turbo and all the fixings to replace everything. I also bought new o2 sensors for good measure.

Should I consider replacing the catalytic converter too, given that it was glowing red multiple times? The catalytic converter looks ok from both ends and flows air fine when air is blown through it using a shop vac. The honeycomb looks intact on both ends and from what I can see in the o2 sensor holes. I read online that overheating the cat is essentially a death sentence but don’t want to waste money replacing something that may not need replacement.

Thoughts?

[IraHayes]

Based on everything that you’re saying, to me it sounds like a bad cat. But you say you inspected it and it looks good, so I don’t know. Give or take 100,000 miles is about the average life expectancy for a cat. Is there any kind of a sulfur smell coming from the exhaust when the car is running? If there is, the cat is pretty much done.

[lilfoot]

Originally Posted by IraHayes

Based on everything that you’re saying, to me it sounds like a bad cat. But you say you inspected it and it looks good, so I don’t know. Give or take 100,000 miles is about the average life expectancy for a cat. Is there any kind of a sulfur smell coming from the exhaust when the car is running? If there is, the cat is pretty much done.

Nope, no smell. The exhaust has been pretty sooty for the last 20k miles or so but I figured that was my heavy throttle foot.

[IraHayes]

I’m still inclined to think it’s the cat with that kind of mileage and the exhaust glowing cherry red as you described. I only say that because when the catalytic converter’s on two previous cars I owned failed, they were glowing cherry red right before. At your current mileage, I would just replace it because it’s likely near the end of its lifespan.

[F32Fleet]

Did you spray anything down the intake?