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Hi my light came on again for cat bank 1 under efficiency, car has 120000 miles on the clock, is this expected to go belly up now? Car does usually run on lpg. At least last 30 to 40,000 miles. I've been through tanks of lucas upper cylinder lubricant, two of the cataclean too, so looks like I need to replace depending on getting some expert opinion / diagnosis on the O2 sensors cuz they are to go at 120000 miles. Thanks in advance
 

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Curiously after thrashing the car about with a bottle of lucas upper cylinder lubricant in 1/3 tank shell v power 99 the engine light just turned off all by itself.
 

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My 330ci also runs on LPG and has recently thrown the engine light (mostly O2 sensor/lean codes). I think there must be an air leak somewhere. Best bet is to take it to the garage to do a smoke test, rather than just change the cat (which you might not need to change anyway). Mine is on 190k miles and on LPG since 120k. Also, have you had an LPG service recently? Might be worth a try.
 

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My 330ci also runs on LPG and has recently thrown the engine light (mostly O2 sensor/lean codes). I think there must be an air leak somewhere. Best bet is to take it to the garage to do a smoke test, rather than just change the cat (which you might not need to change anyway). Mine is on 190k miles and on LPG since 120k. Also, have you had an LPG service recently? Might be worth a try.
Wow always nice to see a fellow lpg user!

It had a smoke test back in April last year though I haven't had any lean codes for a long while. The car has cut out a couple of times in last six months, car engine was hot and I was either coasting or stopping on both occasions.
 

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Hi Walrus, yes LPG is definitely a great thing and it is a shame that it looks like the writing is on the wall for it here (but that is another very long debate/topic). Unfortunately I am no expert on fuel trims, but as I see it, the Short Term Fuel Trims (STFT) are constantly making small adjustment to provide the ideal fuel/air mixture, once the adjustments get too high (+/- ve) we get an Engine light. As the STFT are changing, the Long Term trims are learning, so if your SFTF is above +5 (say fluctuating between 5 and 14) all the time, then the LTFT will rise to +5 and the STFT adjustment will be now only be fluctuating to +9 (as the LTFT is now at +5)...This is how I understand it and I may be wrong.
Also, I have not had a chance to resolve my lean codes (some of the codes also indicated prpblems with the 2 post cat sensors), but I took the car to an LPG specialist in Yorkshire, to make sure that the LPG is spot on. He confirmed that it was, but did say that as I had already changed the 2precat O2 sensors, I should really change the post cat sensors too (as they were showing errors too). I got the sensors, just need to find time/money to fit them. So maybe before you change your CAT, try changing the 2 post cat O2 sensors..it might help. Will update once I get round to doing mine.
 

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Is this instruction referring to using the brake vacuum hose like those people using seafoam are doing?


Connect the infusion device with the can. Insert the infusion needle into the engine rubber air intake vacuum tube and hang the can upside down to start the infusion. Let the engine run under stationary conditions at 1,500 rpm approximately for 30-45 minutes. Use this product outdoors. In case the exhaust manifold burns red due to high temperature of the catalytic converter, immediately stop the cleaning process.
 
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