Is your coolant level dropping and nobody can find a leak? On a supercharged Audi, the usual suspect is hiding under the blower: the factory plastic Audi 3.0T thermostat housing. It cracks, it warps, and it takes a full day of labor to reach. The fix is to replace it once with something that won't fail again. Our billet aluminum Audi 3.0T thermostat housing is machined from 6061-T6, keeps the factory OEM+ design, and adds recessed screws. It costs about $100 less than the premium-priced billet housings we researched.
Why the Factory Audi 3.0T Thermostat Housing Fails
The EA837 3.0T is a great engine with one bad habit. Audi put its thermostat in a plastic housing and buried it in the hottest part of the engine, the valley under the supercharger. Every drive heats it up and every cold start shrinks it back down. After enough of those cycles the plastic turns brittle. The mounting tabs crack, the seal surfaces warp, and coolant starts weeping into the valley where you can't see it.
Common symptoms include:
- ✅ Coolant level slowly dropping with no puddle under the car
- ✅ A sweet coolant smell after a drive, or crusty residue in the valley
- ✅ A slow warm-up, or a temperature gauge that wanders
- ✅ The radiator fan running hard, plus coolant temperature warnings or thermostat circuit codes
The part is cheap. The labor to reach it isn't. Owners have reported dealer quotes from roughly $750 to $1,500 for this job, most of it for removing and reinstalling the supercharger. That's the Audi Tax in its purest form. So why would you pay that labor bill and then bolt the same plastic part back in?
What to Look for in a Billet Thermostat Housing
A metal housing isn't automatically a good housing. Here's what matters:
- ✅ 6061-T6 billet aluminum, anodized. It won't crack from heat cycles like the factory plastic does.
- ✅ Factory geometry. It should mount, seal and route coolant exactly like the original, so nothing about your cooling system changes except the durability.
- ✅ An OE-spec thermostat. The engine should warm up and hold temperature the way Audi calibrated it. Some early billet designs on the market drew reports of overcooling in cold climates, which is exactly what you don't want.
- ✅ Smart fastener design. Screws should stay out of the way of the seal and the tight space under the supercharger.
- ✅ OE gaskets and new hardware included, so you aren't sourcing seals on install day.
- ✅ Fitment by engine generation. Gen 1 and CREC engines take different housings.
OEM+ by Design: Built the Way Audi Intended
We didn't redesign Audi's cooling system. We fixed the one part of it that fails. The Vorsprung housing follows the factory layout, uses the factory mounting points and seals with OE gaskets, so your 3.0T warms up and regulates temperature the way Audi intended. That's what OEM+ means to us: the same design, built from a material that lasts.
The complete kit comes pre-assembled with an OE-spec thermostat: Motorad in the Gen 1 housing and Rein in the CREC housing. You get factory-correct temperature control without guessing on a racing thermostat or an aftermarket insert. Prefer to supply your own? The housing-only option includes everything except the thermostat.
The Recessed Screw Upgrade
The housing uses recessed assembly screws. The screw heads sit down in the housing instead of standing proud of it. That keeps the fasteners clear of the sealing area and out of the way in the tight space under the supercharger. It's a small detail, but small details decide whether a cooling part stays dry for 100,000 miles.
Vorsprung vs Premium-Priced Billet Housings vs Dealer Plastic
In short: the Vorsprung billet thermostat housing is $199.99 with an OE thermostat installed, or $149.99 housing only. Premium-priced billet assemblies we researched sell for $299.99. The dealer part is plastic again, and it's the design that failed in the first place.
| Vorsprung billet housing | Premium-priced billet housing | Dealer / OEM plastic | |
|---|---|---|---|
| Material | 6061-T6 billet aluminum, anodized | 6061-T6 billet aluminum, anodized | Plastic |
| Design | OEM+ factory geometry | Billet redesign | Original design that cracks |
| Thermostat | OE-spec thermostat, pre-assembled (Motorad Gen 1, Rein CREC) | Varies by kit | Included with OE assembly |
| Fasteners | Recessed screws, new bolts included | Varies | Factory hardware |
| Gaskets | OE gaskets included | Seals included | Included |
| Price, complete with thermostat | $199.99 | $299.99 | Dealer pricing, plus labor to replace it again |
| Housing only | $149.99 | Varies | Not sold separately |
Ready to fix it for good? Grab the Gen 1 billet thermostat housing or the CREC billet thermostat housing for later cars.
✅ 6061-T6 billet with OE thermostat and gaskets ✅ Fitment help from real 3.0T owners ✅ Fast US shipping
Shop the Billet Thermostat Housing, $149.99-$199.99
What's in the Box
- ✅ Billet 6061-T6 anodized thermostat housing
- ✅ OE-spec thermostat, pre-assembled (complete kit): Motorad on Gen 1, Rein on CREC
- ✅ OE gaskets
- ✅ All hardware, including new bolts
Want extra peace of mind on the seals? Add our TruSeal AFLAS coolant gasket upgrade. It's rated for warmer climates, so check the product page for its temperature range.
Audi 3.0T Thermostat Housing Fitment
Gen 1 (non-CREC) EA837: 2010-2016 S4, 2010-2017 S5 (2010-2012 is the Cabriolet only), 2013-2017 Q5 3.0T, 2014-2017 SQ5, 2009-2011 C6 A6, 2012-2015 C7 A6 and A7, and 2011-2015 Q7. These cars take the Gen 1 billet thermostat housing, which replaces 06E121111AL, 06E121111AD, 06E121111S and 06E121111T.
Gen 2 (CREC) EA837: 2016-2018 C7.5 A6 and A7, 2015-2018 A8 and 2017-2019 Q7. These take the CREC billet thermostat housing.
Not sure which engine you have? Check the engine code sticker, or email help@vorsprungautowerk.com with your VIN and we'll confirm before you order.
Install Notes
- ✅ The supercharger comes off. The thermostat sits in the valley under the blower. Set aside a full day if you're doing it yourself.
- ✅ Use fresh coolant of the correct spec and bleed the system properly afterward. Our G13 coolant guide covers mixing and fill.
- ✅ Clean every sealing surface and install the new gaskets dry unless the instructions say otherwise.
- ✅ Do the whole valley while you're in there. The coolant crossover pipe, Graf metal-impeller water pump and PCV valve all share the same labor.
That last point is why we build our under supercharger kits. They bundle this billet thermostat housing with the other failure-prone valley parts. Read the Audi 3.0T under supercharger kit guide for the full list, or see how these failures fit into the bigger picture in our Audi 3.0T supercharged engine guide.
Audi 3.0T Thermostat Housing FAQ
What is the best Audi 3.0T thermostat housing upgrade?
A billet aluminum housing that keeps the factory geometry, uses an OE-spec thermostat and OE gaskets, and bolts on with no modification. The Vorsprung billet thermostat housing does all of that for $149.99 housing only or $199.99 with an OE-spec thermostat installed (Motorad on Gen 1, Rein on CREC).
Why does the factory 3.0T thermostat housing fail?
The factory housing is plastic. After thousands of heat cycles under the supercharger it turns brittle, the mounting tabs and seal surfaces crack or warp, and coolant starts leaking into the engine valley.
What are the symptoms of a bad 3.0T thermostat or housing?
Coolant loss with no obvious puddle, a coolant smell after driving, a sweet-smelling valley under the supercharger, a slow warm-up, the radiator fan running hard, coolant temperature warnings, and thermostat circuit fault codes.
Do I have to remove the supercharger to replace the thermostat housing?
Yes. On the EA837 3.0T the thermostat lives in the engine valley under the supercharger, so the supercharger has to come off. Plan a full day for a careful DIY, or ask your shop for a quote that includes the supercharger removal.
Which 3.0T thermostat housing do I need, Gen 1 or CREC?
Gen 1 (non-CREC) cars include the 2010-2016 S4, 2010-2017 S5, 2013-2017 Q5 3.0T, 2014-2017 SQ5 and 2012-2015 A6 and A7. The later CREC engine is in the 2016-2018 A6 and A7, 2015-2018 A8 and 2017-2019 Q7. If you are unsure, send us your VIN.
Does a billet thermostat housing change how the engine runs?
It should not. Ours keeps the factory layout and uses an OE-spec thermostat, so the engine warms up and regulates temperature the way Audi designed it. You get a stronger housing, not a different cooling strategy.
Is the billet thermostat housing legal in California?
It is not for sale or use in California on any pollution-controlled vehicle, per the California Air Resources Board. Check your local rules if you live in another state with similar requirements.
What else should I replace while the supercharger is off?
The water pump, coolant crossover pipe, PCV valve, intake manifold gaskets and supercharger vent tube all live in the same area. Our under supercharger kits bundle those parts with this billet thermostat housing so you only pay for the labor once.
Bottom Line on the Audi 3.0T Thermostat Housing
The factory plastic Audi 3.0T thermostat housing is a question of when, not if. The labor to reach it is the expensive part, so fix it once with a housing that keeps Audi's design and drops the plastic. The Vorsprung billet thermostat housing gives you OEM+ geometry, an OE thermostat, OE gaskets and recessed screws, and costs less than the premium-priced alternatives. On a CREC car? Grab the CREC version.
Shop the Billet Thermostat Housing, $149.99-$199.99
Drive the difference. Drive Vorsprung.
Prices checked September 27, 2026 and subject to change. Not for sale or use in California on any pollution-controlled vehicle. Dealer labor figures are owner-reported quotes and vary by shop.
