The 2015 740i with N55 engine is a capable luxury sedan undermined by catastrophic oil consumption issues and expensive transmission cooling failures. When the engine grenades—and many do—you're looking at $15K+ repairs that often exceed the car's value.
N55 Catastrophic Oil Consumption Leading to Engine Failure
Common · high severity
Typical onset: 60,000-100,000 mi
Symptoms: burning 1+ quart per 1,000 miles, blue smoke on cold start, low oil warnings ignored leading to rod knock, complete engine seizure if oil starvation occurs
Fix: Root cause is piston ring land failure and worn valve stem seals. Minor cases need valve seals (12-16 hrs labor). Severe cases require short block replacement or full rebuild with upgraded pistons and rings (40-60 hrs). Many owners don't check oil frequently enough and spin bearings, requiring crankshaft, rods, and full bottom-end work.
Estimated cost: $3,500-18,000
ZF 8HP Transmission Oil Cooler Failure and Fluid Contamination
Common · high severity
Typical onset: 70,000-110,000 mi
Symptoms: transmission slipping or harsh shifts, coolant in trans fluid (strawberry milkshake appearance), transmission overheating warnings, coolant loss with no visible leaks
Fix: Internal oil cooler inside the transmission pan cracks, allowing coolant and trans fluid to mix. Requires transmission drop, full flush, new oil cooler assembly, pan, fluid, and filter. If contamination ran for any length of time, valve body or entire trans may need replacement (add 15-20 hrs). Cooler-only repair is 6-8 hrs.
Estimated cost: $2,200-8,500
Transmission Mount Failure Causing Drivetrain Vibration
Common · medium severity
Typical onset: 50,000-90,000 mi
Symptoms: clunk when shifting from Park to Drive, vibration at idle in gear, excessive movement felt through shifter, visible torn rubber on mount inspection
Fix: Hydraulic transmission mount separates internally. Replacement requires transmission support and partial subframe lowering on some procedures. 3-5 hrs labor depending on access method. OEM mount mandatory—aftermarket fails quickly.
Estimated cost: $800-1,400
High-Pressure Fuel Pump (HPFP) Failure
Occasional · high severity
Typical onset: 80,000-130,000 mi
Symptoms: long crank or no-start when hot, misfires under load, fuel pressure fault codes (P0087, P0090), limp mode with reduced power
Fix: N55 HPFP driven off exhaust cam can fail internally, often dumping metal debris into fuel system. Requires pump replacement (4-5 hrs), injector inspection, and potentially all six injectors if contaminated (add 3-4 hrs and $2K+ parts). Fuel filter replacement mandatory during this job.
Estimated cost: $1,800-5,000
VANOS Solenoid and Eccentric Shaft Sensor Failures
Occasional · medium severity
Typical onset: 60,000-100,000 mi
Symptoms: rough idle especially when cold, loss of power and poor throttle response, check engine light with cam timing codes (P0010, P0013, P0015), mechanical rattle from valve cover area
Fix: Both VANOS solenoids and eccentric shaft position sensor fail on N55. Solenoids are 2-3 hrs each side. Eccentric shaft sensor requires valve cover removal and special tools (5-6 hrs). Often done together during valve cover gasket service to save labor overlap.
Estimated cost: $900-2,200
Coolant System Leaks (Water Pump, Expansion Tank, Hoses)
Common · medium severity
Typical onset: 70,000-120,000 mi
Symptoms: coolant smell after driving, visible drips under engine, low coolant warnings, overheating if ignored
Fix: Electric water pump housing cracks (4-5 hrs), expansion tank splits at seams (1.5 hrs), and plastic coolant pipe connectors become brittle. Water pump is the expensive one; do expansion tank and bleed procedure at same time. System holds pressure poorly as it ages.
Estimated cost: $600-1,800
Owner tips
Check oil every 500 miles religiously—most N55 engine failures stem from ignored oil consumption
Replace transmission fluid and filter every 40K miles regardless of 'lifetime fill' claims
Budget $2,000/year minimum for maintenance after 80K miles
Extended warranty is almost mandatory if buying over 60K miles given engine risk
Avoid unless under warranty or you have a $20K repair fund—the engine time-bomb and transmission issues make this a financial gamble for most used buyers.
AI-assisted summary drawn from NHTSA recall data, our labor-times database, and platform knowledge. Not a substitute for a pre-purchase inspection on a specific vehicle.
Fitment notes: AGM battery required; located in trunk; registered battery replacement requires coding
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Every control module on the 2011-2015 BMW 740i — where it lives, replacement time, and what it takes to program a replacement. Modules marked dealer / factory tool won't work after a part swap alone — budget for programming.
⚠️ Separate modules for driver and passenger. Memory seat, heating, ventilation, massage programming.
Aftermarket tool coverage varies by software version and vehicle build — treat "aftermarket tool" rows as "usually possible" and verify against your tool maker's coverage list before promising a customer. Spot a wrong location or hour? Tell us — corrections ship fast here.
BMW of North America, LLC (BMW) is recalling certain 2013-2015 740i, 740Li, 740Lxi, 750i, 750xi, 750Li and 750Lxi and 2014 ActiveHybrid 7 vehicles. The affected vehicles may have received incorrect replacement left rear taillight assemblies. As such, these vehicles fail to comply with the requirements of Federal Motor Vehicle Safety Standard (FMVSS) number 108, "Lamps, Reflective Devices, and Associated Equipment."
Consequence: Vehicles with the incorrect left rear lamp assemblies may be less conspicuous to other drivers, possibly increasing the risk of a crash.
Remedy: BMW will notify owners, and dealers will inspect the vehicles and replace any incorrect left rear taillight assemblies, free of charge. The recall began August 11, 2017. Owners may contact BMW customer service at 1-800-525-7417.
Performance
Horsepower
320hp
Torque
330lb-ft
0–60 mph
5.3sec
Quarter mile
13.9sec
Top speed
130mph
Fuel economy (EPA)
City
19mpg
Highway
28mpg
Combined
22mpg
Fuel
Premium Gasoline
Capability & size
Curb weight
4,387lb
EPA class
Large Cars
Wiper blades
G11/G12 generation (2016-2022). 2015 model year likely refers to F01/F02 generation (2009-2015) which uses 24/24 with push-button attachment.
Size-standard part numbers — verify your connector type before buying. Rear blades are model-specific; check the package's vehicle list.
Fuel economy figures are EPA data via fueleconomy.gov (median across matching trims). Performance figures are compiled estimates for the 2015 BMW 740i 3.0L I6 Turbo N55 and can vary by trim.
🔧 Database maintained under the daily editorial review of Chris Hackleman · Master Technician · 20+ years and Jeff Moore · Master Lexus & Toyota Mechanic · 20+ years.