ECM-4801 3-Way Cat Code Fix
1999 V70XC 2.4L 5cyl turbo with 352,700 kilometers (approx 220,000 miles) Canada car.
Check engine light was on and code was read as "ECM-4801 Three-way catalytic converter (TWC) efficiency, bank 1".
Searching all the Volvo sites seemed to indicate this could be a few things:
- pre & post o2 sensors faulty
- catalytic converter could be toast
- Fuel injectors
- vacuum leak on intake side or exhaust leak
All of these could be an issue for me based upon mileage plus my cat rattled like it was broken inside when I pounded on it with my fist...
I knew I had an exhaust leak so I started there.
Re & re'ed exhaust manifold from the top. Not fun... Plus my turbo was worn out - the vanes were scraping the housings on both sides! Got a low mileage turbo with reasonably tight bearings and in it went.
This fixed up my exhaust manifold leaks at a couple of the ports but still had exhaust leak. The downpipe flange was difficult to bolt up and after checking this w/o the heat shield on was not sealing at all!
The down pipes on this model is a diabolically designed piece of &%$T! The engineer should be shot with a ball of his own ****! This thing should be two pieces!
You need a hoist to take it out plus need to drop the subframe.
With this much work I was going to replace the cat too! A 1-piece bolt-in was far too many CDN$'s so I elected to have an after market welded in plus replace BOTH the pre & post O2 sensors at same time. With the DP out it was evident that my leak was a broken weld around the flange from the turbo side (flange is tacked in a few places on the backside).
I figure this broken weld is likely due to my son putting this car in a ditch a few years ago...
I had the cat guys weld the flange on too and back together it all went. Code has been clear for 3 days now PLUS mileage is approximately 25% better. The exhaust even smells way less rich at the tailpipe at idle and the exhaust fumes in the car are GONE and it is QUIET! VERY happy about this!
Not a cheap fix, tho. Welded in cat plus 2x O2 sensors plus some shop time on a hoist to wrestle that pig out was just over CDN$1K with our brutal taxes!
I'll give this a few more weeks to really see if this has fixed this 4801 code. This car still has the original MAF and the ETM is the original white label part, too. I am hoping I do not have to get into these for what would be yet another grand...
Last edited by mctee; 10-23-2014 at 11:41 PM.