How Much It Really Costs to Replace a Thermostat in a BMW 335i

Replacing a thermostat in a BMW 335i typically costs between $450 and $900 at a professional shop in the U.S., depending mainly on model year, engine type (N54, N55, or later B-series), labor rates, and whether other cooling-system parts are replaced at the same time. Below is a detailed breakdown of what you are paying for, why prices vary so much, and how to decide between DIY and professional service.

Typical Cost Range for a BMW 335i Thermostat Replacement

The thermostat on a BMW 335i is an electronically controlled unit integrated into the cooling system, which makes it more expensive and labor‑intensive to replace than on many non‑luxury cars. Costs also fluctuate by region, workshop type, and your specific 335i generation.

Average Price Breakdown (Parts and Labor)

The following list explains the common cost components you can expect when replacing a thermostat on a BMW 335i at an independent European specialist or dealership.

• Total typical range: $450–$900
• Parts (thermostat assembly): $150–$350
• Additional parts often replaced: $50–$250 (hoses, clamps, coolant, possibly water pump)
• Labor: $300–$600 (2–4 hours at $120–$200+/hr, depending on shop and region)
• Dealer pricing: Commonly at the upper end: $650–$900+
• Independent specialist pricing: Roughly $450–$750 in most markets

Taken together, these figures explain why owners often encounter a wide estimate spread. A basic thermostat-only job at an independent shop will sit at the low end of the range, while dealer work with extra parts will push the bill toward the top.

How Costs Vary by Model Year and Engine

The BMW 335i has appeared in several generations, each with its own engine layout and slightly different parts and labor profiles. That influences what a thermostat replacement ends up costing.

E90/E92/E93 335i (2007–2013, N54 & N55 Engines)

The list below outlines what owners of the early 335i generations (sedan, coupe, and convertible) can expect.

• Engines: N54 (twin-turbo, 2007–2010) and N55 (single-turbo, 2011–2013)
• Thermostat part cost: ~ $160–$280 for quality OEM or OE-equivalent
• Labor time: Typically 2–3 hours, sometimes more if bolts are corroded or access is tight
• Typical shop total: $450–$800 at independents, $650–$900+ at dealerships
• Common add-on: Electric water pump replacement at the same time, which can add $600–$1,200 to the visit if done together

On these models, the electric water pump and thermostat are located close together. Because they tend to fail within similar mileage windows (often between 70,000 and 120,000 miles), many shops recommend doing both at once to save future labor.

F30/F32 335i (2012–2015, N55 Engine)

The F30/F32 generation 335i uses an updated layout but similar fundamental hardware, keeping costs in a comparable band.

• Engine: N55 single-turbo inline‑six
• Thermostat part cost: ~ $170–$300
• Labor time: 2–3.5 hours, depending on shop familiarity and options fitted
• Typical shop total: $500–$850, with dealers tending higher
• Additional parts: New coolant (BMW‑approved), possibly hoses or plastic fittings if brittle

Though labor techniques differ slightly between E‑series and F‑series cars, the financial impact for thermostat replacement remains broadly similar for most owners.

Parts: OEM vs Aftermarket and What’s Usually Included

Unlike older simple thermostats, the BMW 335i uses an electronically controlled thermostat assembly with integrated housing. That complexity is what drives the higher parts price compared with many non‑German cars.

Thermostat Assembly and Related Components

The following list outlines the main parts that may be used or suggested during a thermostat replacement on a 335i.

• Electronic thermostat assembly: The main unit, with housing and temperature control electronics
• Coolant (antifreeze): Genuine BMW or BMW‑approved coolant, typically 1–2 gallons mixed
• Gaskets and O-rings: Seals between thermostat, pump, and hose connections
• Hoses and clamps: Sometimes replaced if swollen, cracked, or corroded
• Water pump (optional but common add‑on): Frequently recommended as a preventive replacement when doing the thermostat on higher-mileage cars

Choosing OEM or OE-equivalent brands (such as Pierburg, Mahle, or Behr for many BMW applications) generally offers the best balance of reliability and cost, while very cheap off‑brand parts can lead to repeat failures and more labor later.

Labor: Why It’s Not a Quick Budget Job

The 335i’s packaging, turbocharging, and electric water pump design make the cooling system more complex than on simpler engines, and that complexity is reflected in labor charges.

What the Mechanic Actually Does

The list below summarizes typical steps involved when a shop replaces a thermostat on a BMW 335i.

• Diagnosis and confirmation: Scanning fault codes, checking coolant temperature data, and inspecting for leaks
• Coolant drain: Draining part or all of the system to access the thermostat without spillage
• Component removal: Removing undertrays, intake ducts, and sometimes additional components for access
• Thermostat replacement: Unbolting the old thermostat, cleaning mating surfaces, installing the new unit with fresh seals
• Coolant refill and bleeding: Refilling with proper coolant mix and using BMW’s electric bleed procedure to remove air
• Testing: Clearing codes, test‑driving, and rechecking for leaks and correct temperature regulation

Because access can be tight and proper bleeding is crucial, even experienced technicians need a couple of hours to do the job correctly, which explains the substantial labor portion of the final bill.

DIY vs Professional: Potential Savings and Risks

Some BMW owners consider doing a thermostat replacement at home to save money, but the difficulty and risk level is higher than on many mainstream cars, especially for those without prior European-car experience.

What DIY Owners Can Expect to Spend

The following list shows a typical cost profile for a competent DIYer replacing the thermostat on a 335i.

• Thermostat (OEM/OE-equivalent): $160–$300
• Coolant and supplies: $40–$100 (coolant, distilled water, clamps, basic consumables)
• Tools: May need Torx bits, hose clamp pliers, jack stands, and ideally a scan tool or app to monitor temps
• Total DIY cost: ~ $200–$400 if you already own basic tools
• Time investment: 3–6 hours for a first‑timer, faster for experienced hobbyists

DIY can cut the out‑of‑pocket bill roughly in half, but mistakes—like improper bleeding, using the wrong coolant, or damaging plastic fittings—can lead to overheating or future failures that erase those savings quickly.

Signs Your 335i Thermostat Needs Replacement

Thermostat issues on a BMW 335i can present subtly at first, then escalate into overheating or poor performance if ignored. Knowing the warning signs can help you plan the repair before major damage occurs.

Common Symptoms and Their Implications

The following list describes typical indicators that the thermostat may be failing on your 335i.

• Check Engine Light: Often with codes like P0128 (coolant temperature below thermostat regulating temperature) or BMW‑specific thermostat plausibility faults
• Engine running too cool: Gauge or live data shows the engine not reaching normal operating temperature, leading to poor fuel economy and emissions
• Overheating or rapid temperature spikes: Less common but more serious; can indicate the thermostat is stuck closed or partially blocked
• Electric fan running frequently: The fan may run at high speed to compensate for abnormal coolant temperature readings
• Inconsistent cabin heat: Fluctuating interior heat output due to unstable coolant flow

If you notice any of these symptoms, especially in combination or alongside stored codes, a prompt inspection is wise; continuing to drive an overheating 335i risks expensive head gasket or engine damage.

How to Get an Accurate Estimate

Because shop rates and parts choices vary widely, getting a tailored quote is important before scheduling the repair.

Steps to Take Before Committing to a Shop

The following list outlines how to secure a realistic, transparent thermostat replacement estimate for your specific 335i.

• Gather your details: Provide model year, last 7 of VIN, current mileage, and any trouble codes if available
• Ask for a line‑item quote: Request parts, labor hours, shop rate, and coolant/fees to be listed separately
• Clarify parts quality: Confirm whether they’re using OEM, OE-equivalent, or aftermarket components
• Discuss the water pump: Ask if they recommend replacing the electric water pump at the same time and why
• Compare 2–3 shops: Include at least one European specialist and, if possible, a BMW dealer for reference

By standardizing the information you provide and the questions you ask, you’ll get quotes that can be meaningfully compared and avoid surprise charges once the car is already on the lift.

Summary

For a BMW 335i, a thermostat replacement usually runs between $450 and $900 at a professional shop, with the bulk of the cost split between a relatively expensive electronic thermostat assembly and 2–4 hours of labor. Older E90/E92/E93 and F30/F32 335i models fall into similar ranges, though final pricing depends on local labor rates and whether related components—most notably the electric water pump—are replaced at the same time. DIY owners can often complete the job for $200–$400 in parts and fluids but must be prepared for tight access and precise coolant bleeding procedures. Recognizing early symptoms, asking for itemized estimates, and choosing reputable parts and shops are the best ways to control costs and protect the longevity of your turbocharged BMW inline‑six.

How much does it cost to replace a thermostat on a BMW?

The average cost for a BMW 328i Thermostat Replacement is between $480 and $729. Labor costs are estimated between $198 and $290 while parts are priced between $283 and $439.

Can I drive my BMW with a bad thermostat?

Driving with a failed thermostat can lead to problems as it may cause the engine to run too cold, potentially resulting in damage, or it could lead to overheating. If the thermostat is stuck open and causing the engine to run cold, using the vehicle for a short period of time is unlikely to cause an issue.

How much will a mechanic charge to replace a thermostat?

If you prefer to leave the work to a professional, the cost of hiring a mechanic to replace your thermostat typically ranges from $150 to $500, depending on your vehicle’s make and model. While this option is more expensive, it ensures that the job is done correctly and often comes with a warranty on parts and labor.

Is the 335i expensive to maintain?

The annual maintenance cost of a BMW 335i is $1,030. Repair and maintenance costs vary depending on age, mileage, location and shop.