3104

What the Code Means

3104 is logged when misfires are caused by injector problems in stratified charge mode. It's specific to BMW direct-injection engines N43 and N53.

In stratified charge mode, the injector's fuel spray must be aimed precisely near the spark plug — that's the only way the mixture at the electrode ignites on a lean charge. If the spray hits the plug and floods it, or points too far from the electrode, the mixture goes lean. Either way, you get misfires.

The problem is specific to stratified mode: the engine can run fine in homogeneous mode, which sets this code apart from typical ignition system faults.

Symptoms

• Misfires in stratified charge mode;
• rough idle in stratified mode;
• stumbling under lean combustion;
• increased fuel consumption;
• the engine may still run fine in homogeneous mode.

Diagnosis and Repair

1. Pull the fault codes with ISTA or INPA and confirm the misfires are tied to stratified charge mode.
2. Run the injector chemical test (F5 / Shift+F6 / F3) and check live data (F5 / Shift+F6 / F1).
3. Inspect the injector spray pattern: if the fuel spray is aimed wrong, replace the faulty injector.
4. Install OEM injectors only — for example, 13537585261-12 for the N53.
5. Reset the adaptations and take a test drive in stratified charge mode to confirm the misfires don't return.

Secondary Damage

• Persistent misfires damage the catalytic converter from unburned fuel;
• fuel fouling of the spark plugs;
• in severe cases, fuel dilution of the engine oil, which leads to bearing wear.