P0131 on the 2023 Honda Ridgeline
The 2023 Honda Ridgeline continues with the 3.5L V6 (280 hp), 9-speed automatic, and standard AWD. P0131 indicates the upstream O2 sensor on Bank 1 (rear cylinder bank) is stuck at low voltage. At 2023 model mileage (typically 15,000–40,000 miles), this code on a relatively new truck points to a sensor defect, wiring issue, or exhaust leak rather than normal wear.
Sensor Location
Bank 1 Sensor 1 is on the rear exhaust manifold of the transverse-mounted V6, between the manifold and the rear catalytic converter. Access is from underneath the Ridgeline. The truck's higher ride height helps somewhat, but the rear bank is still close to the firewall.
Symptoms
- Check engine light on
- Lower fuel economy
- Rough idle
- Acceleration hesitation
- Emissions test failure
- ECM may over-fuel Bank 1
Causes
1. O2 Sensor Defect — High Likelihood
At this low mileage, a manufacturing defect in the Denso sensor is the most probable cause. The sensor's internal element or heater can fail prematurely. This should be handled under warranty.
2. Wiring Issue — Medium Likelihood
A factory assembly error — pinched wire, loose connector, or improperly routed harness — can cause low voltage. The rear bank wiring on the Ridgeline runs through a tight space that's susceptible to assembly variations.
3. Exhaust Leak — Medium Likelihood
An improperly torqued manifold bolt or damaged gasket during assembly can cause an exhaust leak near the sensor. The Ridgeline's truck-duty vibrations may also loosen joints over time, even on a relatively new vehicle.
4. Software Calibration — Low Likelihood
Honda may have a software update that adjusts O2 sensor monitoring parameters. Check for TSBs at the dealer.
Diagnostic Steps
- TSB check — Always first on a newer vehicle.
- Monitor sensor voltage — Stuck below 0.2V confirms P0131.
- Compare banks — Normal Bank 2 confirms Bank 1-specific issue.
- Inspect wiring — Check harness and connector in the rear bank area.
- Exhaust inspection — Look for leaks at the rear manifold.
Warranty
The 2023 Ridgeline has Honda's 3-year/36,000-mile basic warranty, 5-year/60,000-mile powertrain warranty, and federal emissions warranty (8 years/80,000 miles). P0131 should be covered under warranty — visit your Honda dealer.
Costs (if out of warranty)
- O2 sensor (OEM): $200–$365
- Wiring repair: $100–$250
- Exhaust manifold gasket: $260–$520
- Software update: $0–$150
Dealer Service Recommended
On a 2023 Ridgeline under warranty, the dealer is the clear best choice. Honda's HDS provides detailed diagnostic data, and the repair should be at no cost. Don't attempt extensive DIY on a warranty vehicle.