BMW 3 Series E90 320d N47 2.0d 177bhp — Starter Motor Solenoid / Brush Wear
The starter motor wears out internally. This is particularly common on vehicles equipped with Stop/Start systems.
Severity
SevereDIY Difficulty
Moderate
Est. Cost
£150–£350
OBD Codes
None
Symptoms
- A single loud 'click' when turning the key, but engine doesn't crank
- Engine cranks very slowly despite a fully charged battery
- Whirring or grinding noise after the engine starts
Root Cause
The carbon brushes inside the motor wear down to the copper wiring, or the contacts inside the solenoid burn out from repeated arcing.
How To Fix
- Confirm battery voltage is strong under load (to rule out a dead battery).
- Replace the starter motor unit.
- Ensure main earth straps from engine block to chassis are clean and tight.
- Cost: £150-350
Estimated Repair Costs
| Repair Option | Est. Cost (GBP) |
|---|---|
| DIY (parts only) | £60–£140 |
| Independent Garage | £150–£350 |
| Main Dealership | £240–£560 |
Other Faults on This Variant
N47 Timing Chain Failure (Rear of Engine)
CriticalThe BMW N47 diesel engine has a timing chain positioned at the REAR of the engine, against the bulkhead. Chain failure is catastrophic, and repair requires engine removal. This is the most significant known fault in the BMW 3 Series range.
Swirl Flap Failure and Engine Ingestion
CriticalThe N47 intake manifold has metal swirl flaps on actuator rods. When the rods corrode and snap, the flap breaks off and gets ingested into the engine, causing severe internal damage.
EGR Cooler and Valve Failure
ModerateEGR cooler failure on the N47 is common from 70,000 miles. Coolant leaks into the intake manifold and the EGR valve sticks, causing power loss and rough running.
Disclaimer: Repair cost estimates are indicative and based on community data. Always get a quote from a qualified mechanic before proceeding with any repair.