The Honda diagnostic trouble code 61-11 indicates an electrical malfunction in the Bank 1 Secondary Heated Oxygen Sensor (HO2S) heater circuit. This component monitors exhaust oxygen levels post-catalyst, and failure can trigger the check engine light or reduced fuel efficiency. Address it promptly with these steps:
Diagnostic & Repair Procedure
Required Tools: Digital multimeter, basic hand tools, jack and jack stands.
Step 1: Preliminary Safety Checks
- Disconnect the negative battery terminal before inspection.
- Allow the exhaust system to cool completely (minimum 1 hour after driving).
- Verify wiring integrity: Visually inspect the Bank 1 HO2S harness near the downstream catalytic converter for damage, chafing, or corrosion.
Step 2: Heater Circuit Resistance Test
- Unplug the sensor electrical connector. Set multimeter to Ω range.
- Measure resistance between terminals 1 and 2 (consults repair manual for terminal ID specifics).
- Expected reading: 5-25Ω at room temperature. ∞ (open) or near-0Ω indicates sensor replacement required.
Step 3: Power Supply Verification
- Reconnect the battery. Turn ignition ON (engine off).
- Back-probe terminal 1 (power supply wire) with multimeter in DCV mode. Ignition on voltage must be 12V ±0.5V.
- No voltage? Check corresponding fuse in engine bay fuse box.
Step 4: Ground Circuit Test
- With ignition ON, measure voltage between terminal 2 (ground wire) and battery negative. Acceptable reading: ≤0.2V.
- Higher voltage indicates poor ground: Trace wire to chassis ground point, clean corrosion, and tighten.
Step 5: Sensor Replacement Protocol
- If above tests confirm sensor failure, replace with Honda-approved Denso or NGK component.
- Apply anti-seize to threads only (avoid contaminating sensing element).
- Torque to 32-40 N∙m per specification. Route wiring away from heat sources.
Step 6: Post-Repair Verification
- Clear DTC with OBD-II scanner.
- Perform test drive: The code shouldn’t reappear within 2 drive cycles.
- Confirm closed-loop fuel control via live OBD data if accessible.
Critical Safety Notes: Never test wiring with engine running. Wear eye protection when working under vehicle. If PCM/heater driver circuit faults are suspected, professional diagnosis is mandatory.
