BMW 1 Series: N54 Direct Injection Fuel Injector Failure

The high-precision direct injection system on the N54T engine fitted to the 1 Series M Coupe is subject to injector failure from internal seal degradation and carbon deposit buildup on injector tips. BMW issued TSB SI B01 02 15 extending the limited warranty for N54 fuel injectors to 10 years or 120,000 miles, formally acknowledging systemic injector reliability issues. Failure of one or more injectors produces cylinder-specific misfires and lean fuel trim faults. Unlike port-injected engines, direct injection injectors are also susceptible to coking because fuel does not wash the intake valves.

• Engine misfire at idle or under load, particularly on a specific cylinder
• Rough running and hesitation during acceleration
• Fault codes for injector circuit malfunction or cylinder-specific lean mixture
• Increased fuel consumption and occasional cold-start roughness

1. 1

   Scan ECU for injector balance, misfire, and lean fuel trim fault codes identifying specific cylinders.

2. 2

   Ask whether any injectors have been replaced and how many.

3. 3

   Confirm BMW warranty extension eligibility (TSB SI B01 02 15) via VIN and service history.

4. 4

   Perform a cold start observation for rough running in the first 30 seconds.

Parts involved: Fuel injector.

$500 to $3,800 at New Zealand independent workshop rates. That is for this job on its own, not for the car.

An estimate, in NZD, for the repair as normally carried out. What a specific car costs depends on which part has failed and what it damaged on the way — treat this as the floor for a negotiation, not a quote.

• “Have any fuel injectors been replaced, and how many of the six?”
• “Was the BMW N54 injector warranty extension (TSB SI B01 02 15) applied at a BMW dealer?”
• “Does the engine misfire, run rough, or show a check engine light?”

The failure described above is documented in published sources — owner forums, technical service bulletins, recall notices and workshop write-ups — held in our fault database. The inspection instructions and the cost estimate are KickTyres’ own interpretation of them, and it is a starting point for an inspection rather than a manufacturer statement.