Catalytic Efficiency

[JLowell]

I just bought a super clean 1997 LS 400 with 126,000 miles. It looks like new and the owner had all the service records, etc. The original owner had the engine steam cleaned just before selling it and already had to replace a part on the ignition that the shop told him shorted because of the steam cleaning. Now I have a check engine light and my code reader is telling me it's "catalytic efficiency on 4 banks." I'm now to the code reader and the V-8, but I can't believe that I would have catalytic converter trouble on both exhausts simultanously. Also, I've had three other Toyota to over 200,000 miles and they never had exhaust problems. Anyone every see this type of problem? My only guesses are that it might have something to do with the injector cleaner that the shop put in - again just before it was sold. I got the impression that the original owner wanted everything fixed before he sold it.

[rburg]

I just bought a super clean 1997 LS 400 with 126,000 miles. It looks like new and the owner had all the service records, etc. The original owner had the engine steam cleaned just before selling it and already had to replace a part on the ignition that the shop told him shorted because of the steam cleaning. Now I have a check engine light and my code reader is telling me it's "catalytic efficiency on 4 banks." I'm now to the code reader and the V-8, but I can't believe that I would have catalytic converter trouble on both exhausts simultanously. Also, I've had three other Toyota to over 200,000 miles and they never had exhaust problems. Anyone every see this type of problem? My only guesses are that it might have something to do with the injector cleaner that the shop put in - again just before it was sold. I got the impression that the original owner wanted everything fixed before he sold it.

I feel your pain. Just bought a 95 LS 400 with 259K. 6 hours after I made the purchase the check engine light came on. The dealer said it was the cat's. Think I'll try some of the recommendations about WOT and the seafoam treatment thing. Good luck.

[SRK]

Just because you have a cat code doesn't mean it's the cats. The cats could be overwhelmed by an ignition or fuel system fault. A bad coil affects both banks, but won't pop a code. A bad injector won't pop a code. Keep diagnosing, I'll bet it isn't the cats.

Remember that lots of folks replace O2 sensors because they seem stuck at a high or low value. That proves they are WORKING, and that the fault is upstream.

[billydpowell]

Hi, my 97 LS has 226K on it had has no cat problem, and my 94 LS has 252K on it without cat problems, so look for a reason/problem up on the engine to be causing the failure..

I just bought a super clean 1997 LS 400 with 126,000 miles. It looks like new and the owner had all the service records, etc. The original owner had the engine steam cleaned just before selling it and already had to replace a part on the ignition that the shop told him shorted because of the steam cleaning. Now I have a check engine light and my code reader is telling me it's "catalytic efficiency on 4 banks." I'm now to the code reader and the V-8, but I can't believe that I would have catalytic converter trouble on both exhausts simultanously. Also, I've had three other Toyota to over 200,000 miles and they never had exhaust problems. Anyone every see this type of problem? My only guesses are that it might have something to do with the injector cleaner that the shop put in - again just before it was sold. I got the impression that the original owner wanted everything fixed before he sold it.

[blake918]

My '95 used to randomly throw a P0420/P0430 (maybe 4-5 times over the 4 years/90k miles I had it). I would clear the code and it would go away for a while. I just considered it a "quirk" since I was getting excellent fuel mileage and performance.