how to check for electric power steering (EPS) problems in BMW 3 Series E90/E91

BMW 3 Series E90/E91 (2005-2012)

Error Codes

2-4 hours

Time

medium

Difficulty

medium

Severity

3 min read

575 words

Problem Statement

The vehicle is experiencing issues with the electric power steering (EPS) system, which may result in steering difficulties or unusual behavior in a BMW 3 Series E90/E91.

Estimated Time

2-4 hours

⚠️ Safety Warnings

Important safety information - read before proceeding

•Disconnect battery before working on electrical systems to prevent shock or short circuits.
•Ensure vehicle is securely elevated if accessing components underneath.

Symptoms

•Steering wheel feels heavy or difficult to turn
•Steering assist is intermittent or entirely absent
•Warning light illuminated on the dashboard
•Noises coming from the steering column when turning
•Erratic steering response or self-centering issues

Diagnostic Steps

1
Scan the vehicle’s onboard computer using an OBD-II scanner to check for any error codes related to the EPS system.
2
Inspect EPS fuse and relay for continuity and ensure they are functioning properly.
3
Check the EPS motor connector for corrosion or loose connections.
4
Measure battery voltage to the EPS motor while the ignition is in the “On” position.
5
Test the EPS motor operation by monitoring the current draw with a multimeter while turning the steering wheel.
6
Inspect the steering column and related components for any physical damage or wear.

Solution

💡 Expert Tip

For complex repairs like this, consider taking photos at each step. This helps if you need to reverse a step or consult with a mechanic. Also, keep all removed parts organized - you may need to reference them during reassembly.

Verification

After completing the repair, verify that the issue has been resolved:

✓Test the affected component to ensure it functions correctly
✓Check for any error codes or warning lights
✓Monitor the vehicle for a few days to ensure the issue does not recur

Prevention Tips

To prevent this issue from occurring again:

•Follow the manufacturer's recommended maintenance schedule
•Address warning signs early before they develop into major issues
•Use quality parts and fluids recommended for your vehicle
•Keep detailed records of all repairs and maintenance

Tools & Equipment Required

•OBD-II scanner
•Multimeter
•Torque wrench
•Socket set
•Flashlight

Parts Required

•EPS fuse (if blown)
•EPS motor (if faulty)

Related Faults

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Diagnostic Steps

1
Scan the vehicle’s onboard computer using an OBD-II scanner to check for any error codes related to the EPS system.
2
Inspect EPS fuse and relay for continuity and ensure they are functioning properly.
3
Check the EPS motor connector for corrosion or loose connections.
4
Measure battery voltage to the EPS motor while the ignition is in the “On” position.
5
Test the EPS motor operation by monitoring the current draw with a multimeter while turning the steering wheel.
6
Inspect the steering column and related components for any physical damage or wear.

Solution

1. Preparation

Gather tools: OBD-II scanner, multimeter, torque wrench, socket set, and a flashlight.
Ensure the vehicle is parked on a flat surface with the engine off.
Disconnect the battery to ensure safety while working on electrical components.

2. Inspect and Replace EPS Fuse

Locate the fuse box, typically under the dashboard or in the engine compartment.
Remove the cover and find the EPS fuse.
Use a multimeter to check for continuity in the fuse. If faulty, replace it with a new fuse of the same amperage.

3. Check and Clean EPS Motor Connector

Locate the EPS motor connector, typically situated near the steering column.
Disconnect the connector and inspect for signs of corrosion or dirt.
Clean the connector pins with electrical contact cleaner and reconnect securely.

4. Test EPS Motor Operation

Reconnect the battery.
Using a multimeter, set it to measure current draw.
While having an assistant turn the steering wheel, monitor the current draw of the EPS motor.
If the current draw is outside the manufacturer’s specifications, replace the EPS motor.

5. Replace EPS Motor (if necessary)

Disconnect the battery again for safety.
Remove the steering column cover to access the EPS motor.
Unscrew and disconnect the EPS motor from the steering gear.
Install the new EPS motor, ensuring all bolts are torqued to manufacturer specifications (typically around 10 Nm).
Reconnect the electrical connector and reassemble the steering column cover.