BMW M760i & Rolls-Royce V12 Fuel Injector Guide: Decoding Index Numbers and High Costs

Symptoms of a Failing Fuel Injector

A bad fuel injector on the BMW N74 V12 engine, used in the 2017-2022 BMW M760i, 2016-2021 Rolls-Royce Dawn, 2014-2020 Rolls-Royce Ghost, and 2014-2021 Rolls-Royce Wraith, will cause noticeable engine problems. Symptoms can range from subtle to severe.

• Rough Idle and Misfires: The most common symptom is a rough, shaky idle or engine misfires, which may feel like a stutter or hesitation during acceleration. 🎬 Watch a technician diagnose and repair a Rolls-Royce Ghost misfire. This happens when a cylinder isn't receiving the correct amount of fuel.
• Check Engine Light: A failing injector will almost always trigger the Check Engine Light. Common trouble codes include cylinder-specific misfires (P0301-P0312) or lean/rich condition codes (P0171, P0174).
• Loss of Power: The vehicle may feel sluggish and slow to accelerate as the engine is starved of fuel.
• Fuel Smell: A strong smell of raw gasoline from the engine bay or exhaust is a serious sign. It indicates a leaking injector, where fuel is escaping either externally from the injector body or internally into the cylinder.
• Reduced Fuel Economy: If an injector is stuck open or leaking, it will waste fuel, causing a noticeable drop in your miles per gallon.
• Hard Starting: The engine may take longer than usual to start or may crank without starting if one or more injectors are not functioning correctly.

Part Number and 'Index' Number Explained

These vehicles use a specific type of piezoelectric fuel injector that BMW has updated several times. Understanding the part numbers and 'index' is critical for a successful repair.

• Primary Part Number: The correct and most current OEM part number is 13538616079. This number supersedes several older part numbers.
• Injector Index Number: The most crucial detail is the 'index' number. The latest version is Index 12. This is usually printed on the injector body itself, often as part of a longer number (e.g., 13537585261-12).

Compatibility Warning: Do Not Mix Old and New Injectors

Due to internal construction and calibration differences, you cannot mix injectors of Index 10 or lower with injectors of Index 11 or higher on the same engine bank (one side of the V12). If your engine has older index injectors and one fails, you must replace all six injectors on that bank with the newer index to ensure proper engine balance and performance. Many technicians recommend replacing all 12 at once to prevent future issues.

Known Issues, TSBs, and Recalls

While there are no specific NHTSA recalls for failing fuel injectors on these models, there are related service bulletins and other recalls owners should be aware of.

• No Injector Recall: Searches of the NHTSA database show no recalls for the fuel injectors themselves.
• Emissions Recall (Rolls-Royce): Some 2016-2020 Ghost, Wraith, and Dawn models were part of an emissions recall for the fuel vapor leak detection system (DMTL), which may not illuminate the check engine light during a leak. This is unrelated to injector performance.
• Oil Cooler Line Recall (BMW M760i): Certain 2017-2018 M760i models were recalled for an incorrect engine oil cooler line that could leak oil onto the front brakes, increasing stopping distance.

Diagnosis and Replacement

Diagnosing and replacing these injectors is a complex job that requires special tools and procedures.

Diagnosis Steps

1. Scan for Codes: Start by reading the Diagnostic Trouble Codes (DTCs) to identify which cylinder is misfiring.
2. Swap Coils/Plugs: A common diagnostic step is to swap the ignition coil and spark plug from the misfiring cylinder with a known good cylinder. If the misfire moves, the problem is the coil or plug. If it stays, the injector is the likely culprit.
3. Injector Flow Test: A professional technician with a BMW-specific scan tool can perform an injector balance test, which measures the flow rate of each injector to confirm if one is faulty.

Replacement Procedure & Mandatory Coding

Replacing the injectors is a labor-intensive process that involves removing the engine covers, intake manifold components, and the high-pressure fuel rails.

Installation Difficulty: 4 out of 5. This is a difficult job for a DIY mechanic due to the complexity of the V12 engine, the high-pressure fuel system, and the mandatory coding step.

Injector Coding is NOT Optional: Each individual injector has a unique flow-rate calibration value printed on its body. After a new injector is installed, this number must be programmed into the engine's computer (DME). Skipping this step will cause the engine to run poorly, with a rough idle, poor performance, and incorrect fuel mixtures that could damage the engine or catalytic converters over time. Coding can be performed with dealer software (ISTA), advanced aftermarket scan tools from brands like Autel and Launch, or DIY laptop-based software like INPA.

Buying a Used Fuel Injector

Given the high cost of new injectors, a quality used OEM injector can be a smart purchase. However, there are critical factors to consider for these specific parts.

• Verify the Index Number: This is the most important step. Only purchase a used injector that is Index 11 or, preferably, Index 12. Do not buy any injector with an index of 10 or lower.
• Buy from Reputable Suppliers: Purchase from professional auto recyclers who test and warranty their parts. Avoid unknown sellers, as you cannot determine an injector's condition just by looking at it.
• Inspect for Physical Damage: Before installation, check for any cracks in the plastic housing, bent electrical pins, or damage to the nozzle tip.
• Consider a Matched Set: If you are upgrading from older index injectors, it is best to buy a complete, matched set of 6 (for one bank) or 12 from the same donor vehicle to ensure they are all 🎬 See a comparison between Index 7 and Index 12 injectors. the same revision and have similar wear.
• Why Used OEM is a Good Choice: For a complex electronic part like this, a used OEM injector that has been proven to work is often a more reliable choice than a cheap, unproven new aftermarket part. The precision required for direct injection is extremely high, and OEM parts are built to that standard.

Cost of Replacement

Replacing fuel injectors on the N74 V12 engine is one of the most expensive common repairs for these vehicles.

Note: Costs are estimates and will vary by location and repair shop. Replacing all 12 injectors at a dealership could exceed $12,000.

Frequently Asked Questions