Check Engine Light and/or Engine Overheating Due to Failed Thermostat on Audi A8 Quattro

The thermostat may erratically stick open or closed. The can result in illumination of the Check Engine Light and/or engine overheating.

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Average mileage: 99,405 (24,000–198,000)
Engine affected: 4.2L V8
14 model years affected: 1998, 1999, 2000, 2001, more2002, 2003, 2004, 2005, 2006, 2007, 2008, 2009, 2010, 2011
43 people reported this problem
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Viewing 1 - 18 of 18 problem details
2005 Audi A8 Quattro - 4.2L V8 120,765 mi,
Coolant level is full. No leaks. Temp gauge moves to red after 7 miles driving from cold start.
2005 Audi A8 Quattro - 4.2L V8 26,000 mi,
I had my Audi A8 Quattro 4.2L Parked in my heated garage for 6 weeks i drove it out and after about 15 miles it started running above normal temperature i had to turn the interior heater on to maximum to get the temp back to normal my audi main agent said i needed a new water pump and thermostat at a cost of £1675.53 i was not happy this obviously must be a manufacturers design fault i mean you would not think a £57000 car would need a water pump and thermostat after a mere 26000 mile and it is not soughted yet as i think Audi should rectify the problem or at least meet part of the cost.
2004 Audi A8 Quattro - 4.2L V8 75,000 mi,
Engine suddenly overheated significantly without any previous warning or coolant leakage. Failed thermostat replaced.
1998 Audi A8 Quattro - 4.2L V8 152,000 mi,
my a8 qquatro overheats but does'nt read it on the gage. i had a new waterpump installed> it leaks a little somwhere on the left when parked and turned off and the cooling fas don't continue to cool it when turned off. don" 't know what to do please help.
2004 Audi A8 Quattro - 4.2L V8 24,000 mi,
Thermostat failed closed
2002 Audi A8 Quattro - 4.2L V8 116,500 mi,
Check engine light. Codes said failing thermostat. $871 to fix. Recommended same time do the timing belt, serpentine belt, and water pump with the thermostat, quote, $2065.
2004 Audi A8 Quattro - 4.2L V8 198,000 mi,
Car overheat after driving about 3-10 miles. Fan very loud . When heat is Hi it drives okay .
2005 Audi A8 Quattro - 4.2L V8 68,000 mi,
Thermostat stuck in closed position, engine overheated. Dealer replaced thermostat. In order to do so had to remove timing chain and water pump to get at thermostat. Replaced timing chain and water pump as long as it was all torn apart. Expensive repair for a thermostat. Thought they normally failed in the open position!
2000 Audi A8 Quattro - 4.2L V8 165,000 mi,
Check Engine light on...told by local mechanic that thermostat is stuck open (or so I'm told)...also told it's very expensive to fix, since the whole front end needs to come off to get to fix done.
2011 Audi A8 Quattro - 4.2L V8 56,000 mi,
Thermostat sticking
I'm having the exact same problem.
2005 Audi A8 Quattro - 4.2L V8 55,000 mi,
check engine light came on, pulled entire front of motor to get to thermostat replaced radiator first thinking that could be cause of overheating. replaced timing chain since it was due to be done at 70k anyway. a $150 thermostat in a chevy, costs over 3k in this Audi due to all the items that were done along the way...
2005 Audi A8 Quattro - 4.2L V8 117,000 mi,
Warning light comes on if it is cold out and stays on for about a minute. As the weather became hotter it then began to come on while driving and the temp gauge stats to spike. Opening the reservoir cap and release some pressure and it comes back down and runs normal temp. This happened twice, which makes it appear that the thermostat is stuck closed and is released with the pressure.
2004 Audi A8 Quattro - 4.2L V8 118,480 mi,
It just started to overheat.
2005 Audi A8 Quattro - 4.2L V8 140,000 mi,
Engine overheats unless heater is on HI. Not yet repaired looking for a reasonable and qualified repair technician
2000 Audi A8 Quattro - 4.2L V8 117,089 mi,
Car periodically seems ( per the gauge ) to be running too warm Now the check engine light came on Mechanic told be previously that it's an expensive job to fix and just get used to topping off the coolant from time to time
The the 2004 A8L with 64,500 suddenly overheated. I drove it home (about 3-4 miles) quickly and will bring it in or have it towed in for service tomorrow.
2004 Audi A8 Quattro - 4.2L V8 79,500 mi,
Failed Thermostat