About four months ago, my father changed out the spark plugs on his 2001 V70 non turbo engine. He replace the old plugs with Bosch R3 Platinum 2 plugs. The check engine light came on about 3000 miles after he replaced the plugs. The dealer diagnosed a bad catalytic converter (code 4201). The dealer states that the platinum plugs are what caused the converter to go bad? Is this possible or is the dealer trying to get out of the extended warranty?

Thanks,

George

If it still drives good and the milage is OK, the cat is not bad. The diagnostics are.

Klaus
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(V♂LV♂s 1975 164, 1995 854T, 1998 V70R)

don't know if they caused the failure......

what's wrong with oem plugs ??? I have 2 na cars and always put new set of oem, absolutely no problems with engine, firing, mileage is awesome etc etc etc...

Sounds like TOTAL Bullshit to me. I have been running Platnum plugs in my 2001 T5 for 60 K. THat shouldn't effect it one bit. These Cats almost never go!!!!

J-

Yeah, I agree. About the only thing that will ruin a cat, besides leaded gas that you can't find any more, is running the engine VERY rich for a prolonged peroid of time. The ceramic materal is brittle and can crack with severe impact but I'm guessing it's fine.

bl

I agree with John, although in a hotter turbo engine the Bosch Plats have been known to get too hot and the ceramic insulator crack and fall into the engine. There have been many posts about this so many of us have stopped using them...going back to OEM Volvo plugs. Cats don't go bad in 3000 miles usually. If I were you, I would replace the plugs with OEM's (for your non-turbo), clear the code and keep driving to see if the code comes back. Many different things can set off that light. Besides, code 0421 (warm-up catalytic efficiency below threshold, bank-1)? This and 0420 can also be caused by a loose gas cap if I recall correctly. Besides, there is no connector on the Cat that sends a signal to the OBD-II socket. The Cat is tested by readings from the 02 sensors before and after it (your car has 2). Therefore an 02 sensor going out can make you think it's the Cat. The guy at the dealer should have done more testing before jumping to the conclusion he did. I would say though that for a non-turbo engine, plat. plugs may be too much...in other words, your engine may not have warmed them up enough...thus the code. If you want to stay with Bosch, I would try their straight copper plugs. Many turbo users like these too...they just change them more often. I really don't think your Cat is going out...reset code, tighten gas cap and see what happens. If the code comes back, then change the plugs too, reset the code again and keep driving. AutoZone will read your codes and reset them for free. Good luck!
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1998 S70 T5 Emarald Green Metallic, 2004 V70 2.5T Ruby Red, Previous Owner of Black '94 850 Turbo Wagon. My cars have been running so well lately they've got me worried.