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BMW coolant leaks by engine
Where each common BMW engine tends to lose coolant, how it shows up, and what the fix costs at an independent shop or a dealer. Prices come from our repair pages; leak points come from BMW's own bulletins, NHTSA recalls and the sources linked on each page.
Last updated
N52 / N54 / N55 N20 / N26 B46 / B48 B58 N63 N47 / N57 diesel Is it coolant? Before you pay
At a glance
| Engine | Usual coolant leak points | Priced repairs |
|---|---|---|
| N52 / N54 / N55 | Electric water pump and thermostat; Expansion tank, radiator end tanks and hose quick-connects | N52 / N54 / N55 electric water pump + thermostat |
| N20 / N26 | Electric water pump; Thermostat; Expansion tank and hoses | None yet |
| B46 / B48 | Oil filter housing and oil cooler; Coolant pump; Expansion tank; Coolant lines | B58 / B48 oil filter housing |
| B58 | Oil filter housing and oil cooler; Main coolant pump; Heat management module; Expansion tank; Coolant lines and the electric auxiliary pump | B58 / B48 oil filter housing B58 water pump B58 heat management module replacement B58 coolant expansion tank |
| N63 | Turbo coolant lines and the plastic Y-connector under the turbos; Expansion tank and low-temperature circuit; Turbo auxiliary coolant pump and thermostat | N63 turbo coolant lines |
| N47 / N57 diesel | EGR cooler; Thermostat, expansion tank and hoses | None yet |
Is it coolant?
- A sweet smell after a drive, or white vapour from under the hood that isn't exhaust.
- Dried pink, blue or white crust on plastic parts, hose joints or the expansion tank.
- A low coolant warning that returns after a top-up, especially with no puddle under the car. Coolant that drips onto hot parts often evaporates before it reaches the ground.
- A burning smell with blue-grey smoke is more likely oil on the exhaust. On several of these engines an oil leak sits right next to coolant hoses, so the two get mixed up. Those cases are noted below.
Don't open the expansion tank cap on a hot engine. The system is under pressure and the coolant can scald.
N52, N54 and N55
2006–2018 inline sixes: E90/F30 328i and 335i, 535i, X3, X5 35i, 135i, M235i, Z4
These sixes use an electric water pump bolted low on the front of the engine, with the thermostat attached to it. When the pump gives up it usually stops working rather than dripping, so the first sign is often a temperature warning, not a puddle.
| Where it leaks | What you notice | Our price page (national average) |
|---|---|---|
| Electric water pump and thermostat (front of the engine, below the belt) | Coolant temperature warning or "engine hot" message, reduced power, radiator fan running hard. Water pump fault codes. Can strand the car without warning. | N52 / N54 / N55 electric water pump + thermostat Indie $758–$1,259 Dealer $1,841–$2,250 |
| Expansion tank, radiator end tanks and hose quick-connects | Dried coolant crust on the plastic, a slow drop in the tank level, sweet smell after a drive. Plastic parts get brittle with age and heat. | No price page yet |
| Not coolant, but often mistaken for it: oil filter housing gasket (N55, also N52/N54) | Oil, not coolant, running down the front of the engine and onto the coolant hose at the cylinder head and the belt. Oil-soaked hoses soften over time, so fix this leak early. | N55 oil filter housing gasket (OFHG) Indie $610–$760 Dealer $1,492–$1,970 Indie owners paid $648–$763 |
BMW bulletins on file
- SIB 01 13 21 Class action settlement: N54/N54T/N55 electric engine coolant pump Electric water pump class-action settlement on N54/N55 engines (2007–2019); covers eligible repairs and reimbursement under the court settlement. Service bulletin · May 2021
BMW settled a class action over N54 and N55 electric water pumps; its terms are in bulletin 01 13 21 on file with NHTSA. A BMW center can say whether your VIN still qualifies.
N20 and N26
2012–2018 2.0L turbo fours: F30 320i/328i, F32 428i, F10 528i, X1 28i, X3 28i, 228i, Z4 28i
Like the sixes before it, the N20 uses an electric water pump and a map-controlled thermostat. BMW extended the thermostat warranty on many N20 cars, so check that before paying.
| Where it leaks | What you notice | Our price page (national average) |
|---|---|---|
| Electric water pump (front of the engine) | Coolant temperature warning, reduced power, water pump fault codes. More common at higher mileage. | No price page yet |
| Thermostat | Check-engine light with a thermostat fault, slow warm-up, weak heat. Several BMW warranty extensions cover it on eligible cars. | No price page yet |
| Expansion tank and hoses | Coolant crust or a falling tank level with no warning light yet. | No price page yet |
BMW bulletins on file
- SIB 01 01 16 Thermostat warranty extension Thermostat warranty extension on N20/N52/N55 engines (2012–2017); BMW extended the warranty on this part for eligible cars. Service bulletin · Dec 2017
- SIB 01 17 17 Thermostat warranty extension Thermostat warranty extension on N20 engines (2014–2015); BMW extended the warranty on this part for eligible cars. Service bulletin · Dec 2017
We don't price an N20 water pump or thermostat yet. If you need one, use "Request a price" on any job page and we'll research it. The N20's best-known big repair is the timing chain, which is not a coolant job.
B46 and B48
2016+ 2.0L turbo fours: 330i, 430i, 530i, 230i, X1, X2, X3 30i, X4 30i, Z4 30i
The modular four shares its weak spot with the B58: a plastic oil filter housing that also carries coolant through its oil cooler. A crack or a failed gasket there leaks coolant, sometimes oil too.
| Where it leaks | What you notice | Our price page (national average) |
|---|---|---|
| Oil filter housing and oil cooler | Low coolant warning with no puddle, coolant smell or crust around the housing, sometimes found at an oil change. | B58 / B48 oil filter housing (coolant leak) Indie $1,225–$2,101 Dealer $2,465–$4,010 Indie owners paid $1,800–$3,300 Dealer owners paid $2,825–$3,950 |
| Coolant pump | Coolant loss or a low-coolant warning. Separately, BMW ran a service action to replace the mechanical coolant pump on some G20, G22, G23, G30, G05, G06 and G07 cars built September 2020 to May 24, 2021, because its belt pulley can fracture. | No price page yet |
| Expansion tank | Coolant crust on the tank or at its hose connections, or a level that keeps dropping. | No price page yet |
| Coolant lines | Seeping hose joints. On several G-series models BMW found that quick-disconnect coolant line O-rings can leak at or below 5°F (-15°C). | No price page yet |
BMW bulletins on file
- SIB 11 10 25 Coolant leaking from oil filter housing Oil filter housing leak on BMW G02/G20/G22/G23 and other models (2025); BMW explains the cause and the approved repair. Service bulletin · Dec 2025
- SIB 11 05 21 Service action: replace the mechanical coolant pump Water pump cracking on BMW G05/G06/G07/G20 and other models (2017–2022); BMW repairs affected cars free under a service campaign. Service campaign · Dec 2024
- SIB 17 03 20 Coolant line quick disconnects leak in low temperatures at or below -15˚c (5˚f) Coolant line leak on BMW G01/G02/G05/G07 and other models (2018–2020); BMW gives an inspection and repair procedure. Service bulletin · May 2020
B58
2016+ 3.0L turbo six: 340i, M340i, 440i, M440i, 540i, 740i, X3/X4 M40i, X5/X6/X7 40i, Z4 M40i, Supra
The B58 has more coolant parts than most BMW sixes, including a heat management module (BMW's thermostat), a belt-driven main pump, a small electric auxiliary pump and, on some models, two separate expansion tanks. That means more places to leak, and quotes that bundle several of them.
| Where it leaks | What you notice | Our price page (national average) |
|---|---|---|
| Oil filter housing and oil cooler (back-right of the engine) | Low coolant warning with no visible leak, coolant smell or residue behind the intake, overheating if ignored. | B58 / B48 oil filter housing (coolant leak) Indie $1,225–$2,101 Dealer $2,465–$4,010 Indie owners paid $1,800–$3,300 Dealer owners paid $2,825–$3,950 |
| Main coolant pump (front of the engine) | Coolant crust or a seep at the front, low-coolant warning, overheating warning. BMW replaced the mechanical pump under a service action on some 2020–2021 builds because the belt pulley can fracture. | B58 water pump (coolant pump) Indie $565–$1,084 Dealer $1,180–$2,295 |
| Heat management module (thermostat) | Running hot or slow to warm up, poor heat, thermostat fault codes, a leak from the module itself. | B58 heat management module (thermostat) replacement Indie $978–$1,506 Dealer $2,234–$3,037 |
| Expansion tank (high- or low-temperature circuit) | Low coolant warning that comes back after top-ups, crust or drips on the tank, a charge-air circuit coolant message on the low-temp tank. On some B58 cars BMW traced low-temperature circuit coolant loss to the coolant breaking down and gassing, fixed by draining and refilling twice with HT-12 coolant. | B58 coolant expansion tank (G05 X5 40i, high- or low-temp) Indie $138–$378 Dealer $395–$724 |
| Coolant lines and the electric auxiliary pump | Seeps at hose joints. The small auxiliary pump is a separate part from the main pump, so make sure a quote names the right one. | No price page yet |
BMW bulletins on file
- SIB 11 05 21 Service action: replace the mechanical coolant pump Water pump cracking on BMW G05/G06/G07/G20 and other models (2017–2022); BMW repairs affected cars free under a service campaign. Service campaign · Dec 2024
- SIB 17 02 20 Coolant leaking from the low temperature cooling system (B58C engine) BMW bulletin SI B17 02 20 for G05/G06/G07/F15 (2018–2023): Coolant leaking from the low temperature cooling system (B58C engine). Service bulletin · Aug 2022
- SIB 17 03 20 Coolant line quick disconnects leak in low temperatures at or below -15˚c (5˚f) Coolant line leak on BMW G01/G02/G05/G07 and other models (2018–2020); BMW gives an inspection and repair procedure. Service bulletin · May 2020
- SIB 64 02 21 Check control message “coolant level. too little coolant” Coolant leak on B58/N63 engines (2019–2021); BMW gives an inspection and repair procedure. Service bulletin · Feb 2021
N63 V8
2009+ 4.4L twin-turbo V8: 550i, 650i, 750i, X5/X6 50i, later M550i and M50i models
The turbos sit inside the V of this engine, so coolant lines, the expansion tank and nearby seals live in a lot of heat. Leaks often show up as a low-coolant warning or vapour from the back of the engine rather than drips on the floor.
| Where it leaks | What you notice | Our price page (national average) |
|---|---|---|
| Turbo coolant lines and the plastic Y-connector under the turbos | Low coolant warning with no puddle, sweet smell or white vapour from the top or back of the engine, crust on the connector, drips on the alternator. Scope varies from re-clamping hoses to a full line kit with the turbos removed. | N63 turbo coolant lines (coolant leak in the hot V) Indie $509–$754 Dealer $903–$1,309 Dealer owners paid $2,000–$3,202 |
| Expansion tank and low-temperature circuit | Crust or cracks on the tank, a falling level. BMW has a coolant leak bulletin for the N63R low-temperature circuit and a service action to check the coolant level on some 2017–2019 N63 and S63 cars. | No price page yet |
| Turbo auxiliary coolant pump and thermostat | On the N63R (G12 750i, later G30), BMW bulletins cover a blocked turbocharger auxiliary coolant pump with a "Drive faulty" message, a thermostat service action, and a thermostat warranty extension to 15 years or 150,000 miles. | No price page yet |
| Not coolant: valve cover gaskets | Burning-oil smell and smoke from oil on the hot exhaust. A different leak with its own price page. | N63 valve cover gaskets (both banks) Indie $2,772 Dealer $5,583–$7,425 |
BMW bulletins on file
- SIB 01 01 21 N63R engine thermostat: ltd wty extension to 15 years/150,000 miles Thermostat warranty extension on BMW G05/G06/G07/G11 and other models (2016–2022); BMW extended the warranty on this part for eligible cars. Warranty extension · Nov 2024
- SIB 17 06 17 Coolant leak from low temperature cooling circuit (N63R) Coolant expansion tank leak on BMW G05/G06/G07/G11 and other models (2016–2023); BMW explains the cause and the approved repair. Service bulletin · Dec 2022
- SIB 17 01 19 Coolant expansion tank inspection Coolant expansion tank inspection on N63/S63 engines (2016–2019); BMW gives an inspection and repair procedure. Service bulletin · Apr 2019
- SIB 11 03 16 Water pump fault codes Water pump fault codes on N63 engines (2016); BMW gives an inspection and repair procedure. Service bulletin · May 2016
- SIB 11 10 17 Thermostat leak Thermostat leak on N63 engines (2016); the fix is replacing the affected part. Service bulletin · May 2017
Diesels (N47 and N57)
2014–2018 US diesels: 328d, 535d, 740Ld, X3 xDrive28d, X5 xDrive35d
The diesel coolant issue that matters most is inside the engine: the EGR cooler can leak internally, so coolant mixes with soot. BMW recalled the US cars twice for it and later extended coverage on N47 and N57 EGR coolers.
| Where it leaks | What you notice | Our price page (national average) |
|---|---|---|
| EGR cooler (internal leak) | Coolant level dropping with no outside leak. NHTSA's recall summary says the mix of coolant and soot can lead to smouldering particles and, in the worst case, a melting intake manifold. | No price page yet |
| Thermostat, expansion tank and hoses | The same plastic-part ageing as the petrol engines of the same years. | No price page yet |
Recalls
- NHTSA 18V-755 (2018, 44,368 cars, 2014–2018 328d, 535d, 740Ld, X3, X5): If the EGR cooler leaks internally, the coolant can mix with diesel engine soot.
- NHTSA 21V-907 (2021, 50,404 cars, 2014–2018 328d, 535d, 740Ld, X3, X5): The EGR cooler may leak internally, causing coolant to mix with diesel engine soot, which could result in smoldering particles and a melting intake manifold.
BMW bulletins on file
- SIB 01 05 20 N47/N57 diesel engine EGR cooler revised ext ltd wty (elw) coverage/procedure EGR cooler warranty extension on B46/B48/B47/B58/N20/N47/N55/N57/N63 engines (2014–2018); BMW extended the warranty on this part for eligible cars. Warranty extension · Aug 2025
Recall repairs are free at any BMW center. Check your VIN before paying anyone for an EGR cooler.
Before you pay for a coolant repair
- Run your VIN through our recall check and ask a BMW center about open service campaigns. BMW has replaced mechanical coolant pumps on some 2020–2021 G-series cars under a service action, recalled US diesels for EGR cooler leaks, and extended thermostat coverage on many N20, N26 and N63R cars.
- Ask which part is leaking and how the shop knows. A pressure test or dye shows the source; "coolant leak, replace cooling system" doesn't.
- Check the scope line by line. On B58 and B46/B48 cars, quotes often bundle the oil filter housing with the thermostat, hoses or water pump, which can double the bill.
- Top up only with BMW-approved coolant mixed as the label says, and recheck the level cold for a few days. A dropping level means the leak is still there.
For how dealer and independent prices compare on these jobs, see BMW dealer vs independent shop prices.
How we built this guide
Leak points and symptoms come from our job pages (which link the owner posts behind each price), BMW service bulletins and warranty extensions filed with NHTSA, NHTSA recall reports, and the engine write-ups below. Estimates are national averages built from BMW warranty labor time, regional shop rates and parts prices; open a job page to see prices for your ZIP. "Owners paid" is the middle half of sourced prices and is shown only where we have at least 3 for that shop type. Tax, shop fees and diagnosis aren't included.