P0135 on the 2022 Honda Accord
The 2022 Honda Accord (10th generation) uses either the 1.5L turbocharged K20C4 (192 hp) or the 2.0L turbocharged K20C4 (252 hp). The P0135 code indicates the upstream O2 sensor heater circuit has malfunctioned. The heater element inside the sensor brings it to operating temperature quickly after cold starts, enabling rapid closed-loop fuel control for emissions reduction.
Understanding the Heater Circuit
The O2 sensor heater on the Accord is powered through a dedicated fuse and controlled by the ECM. When you start the engine, the ECM energizes the heater circuit, which draws 1-3 amps through the internal resistance wire to rapidly heat the sensor to approximately 600°F. P0135 sets when the ECM detects an abnormality in this circuit, whether from excessive current (short), no current (open), or resistance outside the expected range.
Common Causes
- Burned-out heater element: The most frequent cause on Accords. The internal resistance wire degrades from thermal cycling. With the 2022 model having 2-4 years of service, premature heater failure can occur from oil contamination or manufacturing variability.
- Blown heater fuse: The underhood fuse box contains a dedicated fuse for the O2 sensor heater circuit. This is the first thing to check and the cheapest possible fix.
- Connector corrosion or damage: The sensor connector on the Accord can develop corrosion from moisture exposure. The 2022 model is young enough that this is less common but can occur in harsh climates.
- Wiring fault: A short or open in the heater circuit wiring between the fuse box and sensor connector. On the Accord, check the wiring near the exhaust manifold where heat can damage insulation.
Symptoms
The check engine light illuminates. Cold-start idle may be slightly rougher for the first 1-2 minutes. Fuel economy on short trips decreases because the engine stays in open-loop mode longer than intended. Once the sensor reaches operating temperature via exhaust heat, normal performance resumes. Most Accord owners notice only the check engine light.
Diagnosis
- Check the O2 sensor heater fuse in the underhood fuse box.
- Disconnect the sensor and measure heater circuit resistance: 2-15 ohms is normal; open circuit means the heater is burned out.
- Verify 12V at the heater power pin with key on.
- Inspect the connector for corrosion or damage.
- If all external checks pass but the code persists, the sensor's internal heater has failed.
Repair Costs
The 2022 Accord may still be under emissions warranty (8 years/80,000 miles). If not: OEM Denso sensor: $85-$180. Aftermarket: $40-$90. Dealer labor: $100-$180. Total: $185-$360. Independent Honda shops: $130-$260. Fuse replacement: under $10.
DIY
Both the 1.5T and 2.0T Accords have accessible upstream O2 sensors. The sensor can be reached from above with a 22mm O2 sensor socket. Always check the fuse first. If sensor replacement is needed, apply penetrating oil, disconnect the connector, and use a ratchet with extension. Total DIY time: 20-40 minutes.