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Title: 2.7t A6/allroad: P2181 - Performance Malfunction in Cooling System Post by: nyet on September 05, 2015, 06:56:30 PM http://wiki.ross-tech.com/wiki/index.php/18613/P2181/008577
Anybody know anything about DTHM? Safe to zero out CWDTHM? Seeing this on some cars even with brand new thermostats/temp sensors etc. Title: Re: 2.7t A6/allroad: P2181 - Performance Malfunction in Cooling System Post by: vwaudiguy on September 05, 2015, 07:17:20 PM Been fixing VW's and Audi's for 13+ years. Never had a problem resolving this fault without software mods.
Title: Re: 2.7t A6/allroad: P2181 - Performance Malfunction in Cooling System Post by: nyet on September 05, 2015, 07:19:10 PM Been fixing VW's and Audi's for 13+ years. Never had a problem resolving this fault without software mods. Radiator issue? What else can go wrong if all temp sensors are brand new? Title: Re: 2.7t A6/allroad: P2181 - Performance Malfunction in Cooling System Post by: vwaudiguy on September 05, 2015, 07:23:22 PM I've seen it be the water pump a few times from low timing belt tension. You probably know this, but this code gets thrown if the car warms up to fast, too slow, or does not maintain it's warm-up temp well. Fans could be a problem, as well as the radiator fan switch.
Title: Re: 2.7t A6/allroad: P2181 - Performance Malfunction in Cooling System Post by: nyet on September 05, 2015, 07:29:00 PM I've seen it be the water pump a few times from low timing belt tension. You probably know this, but this code gets thrown if the car warms up to fast, too slow, or does not maintain it's warm-up temp well. Fans could be a problem, as well as the radiator fan switch. Everything was swapped for these cars, including water pump. Fans are fine. Only thing that remains is the rad. Two diff cars. They don't overheat and they both warm up fine. Is it possible the coolant temp model isn't quite right for aging cars, and the error threshold (5C iirc) is too narrow? Title: Re: 2.7t A6/allroad: P2181 - Performance Malfunction in Cooling System Post by: nyet on September 05, 2015, 07:44:12 PM From the ME7.1 FR, it looks like it should only trigger if the motor warms up too slow... (thmdmm-tmotlin>5C)
Title: Re: 2.7t A6/allroad: P2181 - Performance Malfunction in Cooling System Post by: vwaudiguy on September 05, 2015, 07:54:32 PM From the ME7.1 FR, it looks like it should only trigger if the motor warms up too slow... (thmdmm-tmotlin>5C) This the most common scenario. Have you logged the warm-up cycle? Title: Re: 2.7t A6/allroad: P2181 - Performance Malfunction in Cooling System Post by: armageddon on September 06, 2015, 05:57:18 AM check coolant temperature with vag-com on engine and instruments.
I had this problem and on instruments temperature climb till 90º and stay there, on engine it stops at 80º. It was a new coolant temperature sensor that fail after 1 month. Title: Re: 2.7t A6/allroad: P2181 - Performance Malfunction in Cooling System Post by: turboat on September 07, 2015, 10:04:00 AM Are they both genuine thermostats and genuine temp sensors? I've had issues with aftermarket versions of both.
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