E28 / E34 5-Series

1981-1996 / Sedan / Germany

All E28 / E34 5-Series problems All workshop issues

Critical Electrical

8. E34 General Module (GM5) Failure

Symptoms

Intermittent failures of central locking, interior lights, window operation, mirror adjustment, and various convenience features. Symptoms may be random and inconsistent, one day the central locking works, the next it doesn't.

Cause

The General Module (GM5) is an electronic control unit that manages body electrical functions. The module's circuit board develops cold solder joints and corrosion from moisture ingress, particularly on cars that have had water leaks into the cabin. The GM5 is mounted in the kick panel area, which is vulnerable to water from heater core leaks or door seal failures.

Fix

The GM5 can be repaired by a specialist electronics repairer who can identify and re-solder cold joints and replace corroded components.

Repair cost: $200-400.

Replacement GM5 modules are available from wreckers ($100-300) but must be coded to the car.

New-old-stock modules are scarce.

GM5 coding requires BMW diagnostic software (INPA or equivalent).

Cost mentioned in fix

cost: $200-400$100-300

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Other known issues

Common Electrical

7. E28 Instrument Cluster Pixel Failure

The LCD segments in the instrument cluster fade, become incomplete, or disappear entirely. The odometer, trip meter, clock, and service indicator displays are all affected. In severe cases, the entire LCD is unreadable.

Critical Engine, M30 (E28 535i, E34 535i)

1. Timing Chain and Tensioner Wear

Rattling from the front of the engine on cold startup, lasting several seconds until oil pressure builds. The rattle may also appear briefly when restarting a warm engine. In severe cases, a constant rattle or chain slap noise.

Critical Engine, M30 (E28 535i, E34 535i)

2. Oil Leaks (M30)

Oil weeping from the valve cover gasket, oil filter housing gasket, oil pan gasket, rear main seal, and front crank seal. Oil residue on the underside of the engine and on the exhaust manifold.

Common Engine, M50/M52 (E34 520i, 525i, 530i)

3. VANOS Seal Failure

Rattling from the front of the engine on startup, loss of power and torque below 3,000 rpm, rough idle, and in some cases a check engine light. The engine may feel flat and unresponsive at low RPM but pull normally above 4,000 rpm.

Minor Engine, M50/M52 (E34 520i, 525i, 530i)

4. M60 V8 Nikasil Bore Wear (E34 530i, 540i)

Progressively worsening cold-start difficulty, rough idle when cold that smooths out as the engine warms, increasing oil consumption (more than 1L per 1,000 km), and eventually misfiring and low compression.

Minor Cooling System (Both Generations)

5. Expansion Tank Failure

The expansion tank cracks without warning, dumping coolant. The engine overheats rapidly, often within 5 minutes of the leak starting. The crack typically occurs on the side of the tank or at the plastic seam. On the E34, the tank is mounted on the left inner wing; on the E28, it's on the right.

View all 14 E28 / E34 5-Series problems