Power Steering Service

This procedure covers diagnostic and inspection steps for the electric power steering system on 2016-2021 Honda Civic 1.5L Turbo models, which use an electric motor instead of hydraulic fluid.

Warnings

Tools required

Parts

• EPS control unit (if diagnostic testing indicates failure) × 1 — 39980-TBA-A110 or equivalent OEM

Preparation

1. Park vehicle on level ground and engage parking brake
2. Turn ignition to OFF position
3. Ensure wheels are pointed straight ahead
4. Connect OBD-II scanner to diagnostic port under driver's side dash

Procedure

1. 1

   Verify EPS System Operation
   Start the engine and verify the EPS warning light on the instrument cluster turns off after initial bulb check. Turn the steering wheel lock-to-lock at idle to confirm normal power assist is present. Listen for any unusual noises from the steering column area during operation.
2. 2

   Scan for Diagnostic Trouble Codes
   Using the OBD-II scanner or HDS, navigate to the EPS control module and retrieve any stored or pending fault codes. Common codes include C1611 (EPS motor malfunction), C1613 (EPS control unit malfunction), and U0129 (lost communication with EPS). Record all codes for diagnosis.
3. 3

   Inspect EPS Motor and Connections
   Open the hood and visually inspect the EPS motor assembly located on the steering column below the dashboard. Check the main electrical connector for corrosion, moisture, or loose connection. Verify the ground wire connection is clean and tight. Look for any physical damage to the motor housing or wiring harness.
4. 4

   Test EPS System Voltage
   With ignition ON (engine OFF), use a multimeter to measure voltage at the EPS motor connector. Battery voltage (approximately 12-14V) should be present on the power supply wire. Consult wiring diagram for specific pin locations. Low voltage may indicate a wiring or fuse issue in the EPS circuit.
5. 5

   Check EPS Fuse and Relay
   Locate the EPS fuse (typically 80A) in the under-hood fuse box and the EPS relay. Visually inspect the fuse for any signs of failure or corrosion. Test the relay operation if clicking noise is absent when ignition is turned on. Replace fuse or relay if defective.
6. 6

   Inspect Steering Column Mounting
   Check that all steering column mounting bolts and EPS motor mounting hardware are secure. Loose mounting can cause noise and vibration. If any mounting bolts were loosened during inspection, retighten to specification.
   Torque spec

   Mounting Bolts26 Nm (19 lb-ft)
7. 7

   Perform EPS Calibration if Required
   If any components were replaced or fault codes were cleared, perform EPS steering angle sensor calibration using the HDS. With wheels straight ahead and engine running, follow the scanner prompts to complete the calibration procedure. This ensures proper steering assist calibration and clears adaptation values.
8. 8

   Clear Codes and Test Drive
   Clear all diagnostic trouble codes from the EPS module. Start the engine and verify the EPS warning light remains off. Test drive the vehicle at various speeds, performing gentle and moderate steering inputs to confirm normal power assist operation and absence of warning lights.

Reassembly

1. Ensure all electrical connectors are fully seated and locked in place
2. Verify no tools or parts were left in the engine compartment
3. Reconnect battery if disconnected during service

Verification

• Confirm EPS warning light does not illuminate on instrument cluster during normal operation
• Verify smooth, consistent power steering assist at all speeds with no unusual noises
• Re-scan for diagnostic trouble codes to ensure no new faults are present
• Confirm steering wheel returns to center properly after turns

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