Mishimoto MMTS-GTI-99 99-05 Volkswagen GTI 1.8T 180-Degree Racing Thermostat

The Mishimoto racing thermostat for the 99-05 Volkwagen GTI 1.8T will promote greater cooling efficiency in your stock or modified GTI. Once the engine is fully warmed up, Mishimoto's Volkswagen GTI racing thermostat will open at a lower temperature than standard thermostats. This allows coolant to flow through the engine sooner, which reduces and maintains cooler engine temperatures. The Mishimoto 99-05 Volkwagen GTI 1.8T racing thermostat is the perfect addition to your street or track GTI and is a direct replacement for the stock thermostat. This thermostat includes the signature Mishimoto Lifetime Warranty. Engine coolant thermostat designed to regulate coolant flow and maintain optimal operating temperature. Ensures efficient warm-up, prevents overheating, and supports reliable performance with a precise fit. 1997-2001 Audi A4 Base 1.8 Liter 012, 1997-2001 Audi A4 Base 1.8 Liter 01V, 2003-2006 Audi TT Base 1.8 Liter 09G, 1998 Volkswagen Beetle Base 2.0 Liter 01M, 1998 Volkswagen Beetle Base 2.0 Liter 02J, 1999-2003 Volkswagen Beetle GL 1.8 Liter 01M, 1999-2003 Volkswagen Beetle GL 1.8 Liter 02J, 2003 Volkswagen Beetle GL 1.8 Liter 09G, 1999-2004 Volkswagen Beetle GL 2.0 Liter 01M, 2004 Volkswagen Beetle GL 2.0 Liter 02E, 1999-2005 Volkswagen Beetle GL 2.0 Liter 02J, 2003-2005 Volkswagen Beetle GL 2.0 Liter 09G, 1999-2004 Volkswagen Beetle GLS 1.8 Liter 01M, 2004-2005 Volkswagen Beetle GLS 1.8 Liter 02E, 1999-2005 Volkswagen Beetle GLS 1.8 Liter 02J, 2003-2005 Volkswagen Beetle GLS 1.8 Liter 09G, 1999-2004 Volkswagen Beetle GLS 2.0 Liter 01M, 2004-2005 Volkswagen Beetle GLS 2.0 Liter 02E, 1999-2005 Volkswagen Beetle GLS 2.0 Liter 02J, 2003-2005 Volkswagen Beetle GLS 2.0 Liter 09G, 1999-2004 Volkswagen Beetle GLX 1.8 Liter 01M, 1999-2004 Volkswagen Beetle GLX 1.8 Liter 02J, 2003 Volkswagen Beetle GLX 1.8 Liter 09G, 2001-2002 Volkswagen Beetle Sport 1.8 Liter 01M, 2001-2002 Volkswagen Beetle Sport 1.8 Liter 02J, 2001-2002 Volkswagen Beetle Sport 2.0 Liter 01M, 2001-2002 Volkswagen Beetle Sport 2.0 Liter 02J, 2002-2004 Volkswagen Beetle Turbo S 1.8 Liter 02M, 1998-2005 Volkswagen Golf GL 2.0 Liter 01M, 1999 Volkswagen Golf GL 2.0 Liter 096, 2000-2001 Volkswagen Golf GLS 1.8 Liter 01M, 1999-2005 Volkswagen Golf GLS 2.0 Liter 01M, 2003 Volkswagen Golf GLS 2.0 Liter 09A, 2002 Volkswagen Golf GTI 1.8T 1.8 Liter 01M, 2002-2005 Volkswagen Golf GTI 1.8T 1.8 Liter 02J, 2002-2003 Volkswagen Golf GTI 1.8T 1.8 Liter 02M, 2003-2005 Volkswagen Golf GTI 1.8T 1.8 Liter 09A, 2000-2001 Volkswagen Golf GTI GLS 1.8 Liter 01M, 2000 Volkswagen Golf GTI GLS 2.0 Liter 01M, 1998 Volkswagen Golf K2 2.0 Liter 01M, 1999 Volkswagen Golf Wolfsburg Edition 2.0 Liter 01M, 2003-2005 Volkswagen Jetta GL 1.8 Liter 01M, 2004 Volkswagen Jetta GL 1.8 Liter 09A ...See Application Guide for Additional Fitments

• Lower activation temperature allows coolant to flow through the engine earlier, maintaining lower temperatures (Mishimoto thermostat activates at 180F vs. stock 188.6F)
• Mishimoto Lifetime Warranty
• N/A

The Mishimoto MMTS-GTI-99 racing thermostat is designed for 1999–2005 Volkswagen GTI models equipped with the 1.8T engine. As a direct replacement for the stock thermostat, it regulates coolant flow while supporting efficient warm-up and reliable engine temperature control for street or track use.

Once the engine reaches operating temperature, this thermostat activates at 180°F compared with the stock thermostat’s 188.6°F setting. The lower activation temperature allows coolant to flow through the engine earlier, helping maintain lower engine temperatures in stock or modified applications. The thermostat is also listed for additional Volkswagen, Audi, and related vehicle applications; verify fitment using the application guide before installation.

Key Features & Performance Benefits

• 180°F activation temperature promotes earlier coolant flow.
• Supports cooler engine temperatures compared with the stock 188.6°F thermostat setting.
• Direct replacement design provides a precise fit for applicable vehicles.
• Suitable for street or track GTI applications.

Product Specifications & Technical Data

• Brand: Mishimoto
• Part Number: MMTS-GTI-99
• Product Type: Racing thermostat
• Application: Volkswagen GTI 1.8T
• Activation Temperature: 180°F
• Stock Thermostat Comparison: 188.6°F
• Installation Type: Direct replacement
• Warranty: Mishimoto Lifetime Warranty

What's Included

• One Mishimoto racing thermostat

Fitment

Listed applications include 1999–2005 Volkswagen GTI 1.8T, 2003 Volkswagen Golf, 2003 Volkswagen Beetle, and 2005 Volkswagen Passat. Additional fitments may apply; confirm the vehicle, engine, transmission, and application guide before purchase.

Fitments:
1997 Audi A4 Base
1997 Audi A4 Quattro Base
1998 Audi A4 Base
1998 Audi A4 Quattro Base
1998 Volkswagen Beetle Base
1998 Volkswagen Passat GLS
1999 Audi A4 Base
1999 Audi A4 Quattro Avant
1999 Audi A4 Quattro Base
1999 Volkswagen Beetle GL
1999 Volkswagen Beetle GLS
1999 Volkswagen Beetle GLX
1999 Volkswagen Golf GL
1999 Volkswagen Golf GLS
1999 Volkswagen Golf GTI
1999 Volkswagen Golf Wolfsburg Edition
1999 Volkswagen Jetta GL
1999 Volkswagen Jetta GLS
1999 Volkswagen Jetta Wolfsburg Edition
1999 Volkswagen Passat GLS
2000 Audi A4 Base
2000 Audi A4 Quattro Avant
2000 Audi A4 Quattro Base
2000 Audi TT Base
2000 Audi TT Quattro Base
2000 Volkswagen Beetle GL
2000 Volkswagen Beetle GLS
2000 Volkswagen Beetle GLX
2000 Volkswagen Golf GL
2000 Volkswagen Golf GLS
2000 Volkswagen Golf GTI GLS
2000 Volkswagen Jetta GL
2000 Volkswagen Jetta GLS
2000 Volkswagen Passat GLS
2001 Audi A4 Base
2001 Audi A4 Quattro Avant
2001 Audi A4 Quattro Base
2001 Audi TT Base
2001 Audi TT Quattro Base
2001 Volkswagen Beetle GL
2001 Volkswagen Beetle GLS
2001 Volkswagen Beetle GLX
2001 Volkswagen Beetle Sport
2001 Volkswagen Golf GL
2001 Volkswagen Golf GLS
2001 Volkswagen Golf GTI GLS
2001 Volkswagen Jetta GL
2001 Volkswagen Jetta GLS
2001 Volkswagen Jetta Wolfsburg Edition
2001 Volkswagen Passat GLS
2002 Audi A4 Base
2002 Audi A4 Quattro Avant
2002 Audi A4 Quattro Base
2002 Audi TT Base
2002 Audi TT Quattro ALMS Edition
2002 Audi TT Quattro Base
2002 Volkswagen Beetle GL
2002 Volkswagen Beetle GLS
2002 Volkswagen Beetle GLX
2002 Volkswagen Beetle Sport
2002 Volkswagen Beetle Turbo S
2002 Volkswagen Golf GL
2002 Volkswagen Golf GLS
2002 Volkswagen Golf GTI 1.8T
2002 Volkswagen Golf GTI 337
2002 Volkswagen Jetta GL
2002 Volkswagen Jetta GLS
2002 Volkswagen Passat GLS
2003 Audi TT Base
2003 Volkswagen Beetle GL
2003 Volkswagen Beetle GLS
2003 Volkswagen Beetle GLX
2003 Volkswagen Beetle Turbo S
2003 Volkswagen Golf GL
2003 Volkswagen Golf GLS
2003 Volkswagen Golf GTI 1.8T
2003 Volkswagen Golf GTI 20th Anniversary
2003 Volkswagen Jetta GL
2003 Volkswagen Jetta GLS
2003 Volkswagen Jetta Wolfsburg Edition
2003 Volkswagen Passat GL
2003 Volkswagen Passat GLS
2004 Audi TT Base
2004 Volkswagen Beetle GL
2004 Volkswagen Beetle GLS
2004 Volkswagen Beetle GLX
2004 Volkswagen Beetle Turbo S
2004 Volkswagen Golf GL
2004 Volkswagen Golf GLS
2004 Volkswagen Golf GTI 1.8T
2004 Volkswagen Jetta GL
2004 Volkswagen Jetta GLI
2004 Volkswagen Jetta GLS
2004 Volkswagen Passat GL
2004 Volkswagen Passat GLS
2004 Volkswagen Passat GLS 4 Motion
2005 Audi TT Base
2005 Volkswagen Beetle GL
2005 Volkswagen Beetle GLS
2005 Volkswagen Golf GL
2005 Volkswagen Golf GLS
2005 Volkswagen Golf GTI 1.8T
2005 Volkswagen Jetta GL
2005 Volkswagen Jetta GLI
2005 Volkswagen Jetta GLS
2005 Volkswagen Passat GL
2005 Volkswagen Passat GLS
2005 Volkswagen Passat GLS 4 Motion
2006 Audi TT Base
2006 Volkswagen Golf GL
2006 Volkswagen Golf GLS
2006 Volkswagen Golf GTI 1.8T
2011 Volkswagen Jetta Base
2011 Volkswagen Jetta S
2011 Volkswagen Jetta TDI
2012 Volkswagen Jetta GLI
2012 Volkswagen Jetta S
2012 Volkswagen Jetta TDI
2012 Volkswagen Jetta TDI Premium
2013 Volkswagen Jetta GLI
2013 Volkswagen Jetta S
2013 Volkswagen Jetta TDI
2013 Volkswagen Jetta TDI Premium
2014 Volkswagen Jetta GLI
2014 Volkswagen Jetta S
2014 Volkswagen Jetta TDI
2014 Volkswagen Jetta TDI Premium
2015 Volkswagen Jetta Base
2015 Volkswagen Jetta GLI SE
2015 Volkswagen Jetta GLI SEL
2015 Volkswagen Jetta S
2015 Volkswagen Jetta TDI S
2015 Volkswagen Jetta TDI SE
2015 Volkswagen Jetta TDI SEL

Air Freight Prohibited: false
Not Carb Approved: false
Ltl Freight Required: false
Prop 65: Y
Part Type: automotive
Epa: N/A
Carb Acknowledgement Required: false
Regular Stock: t
Units Per Sku: 1