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bimmaster
bimmaster, BMW Technician
Category: BMW
Satisfied Customers: 1882
Experience:  3 years dealer experience, master bmw tech
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2002 745i: had a warning to accelerate slowly, drive..catalyst..whats

Resolved Question:

My 2002 745i had a warning to accelerate slowly, drive moderately or catalyst damage may occur. whats that all about???
Submitted: 5 years ago.
Category: BMW
Expert:  bimmaster replied 5 years ago.
Hi, this warning will occur when the engine is misfiring.
This is when one or more cylinders in your engine fail to have complete combustion of the fuel. If this is allowed to continue, the catalytic converter will be damaged.
The cat converter is an expensive part of your exhaust system that reduces emissions.
I would have the vehicle scanned for fault codes then diagnosed why the misfire is occuring. On this model, it's usually caused by bad ignition coils. There is one per cylinder.
Customer: replied 5 years ago.

are they hard to diagnose, expensive to replace??

Expert:  bimmaster replied 5 years ago.
If you have a scan tool, its not too hard to replace. It will tell you which cylinders are misfiring. Then you can swap around the ignition coils and spark plugs to determine which part is bad. About 1-2 hours diagnostic time is normally all that's needed to diagnose. The list price on each coil is $57.
If you're over 160,000 km, then the spark plugs should be replaced, if they have not been done yet.
bimmaster and 2 other BMW Specialists are ready to help you
Customer: replied 5 years ago.
thanks very much!!