Understanding P0135 on Your 2020 Pathfinder
Your 2020 Nissan Pathfinder has triggered a P0135 diagnostic code, indicating a malfunction in the oxygen sensor heater circuit for Bank 1, Sensor 1. The 2020 Pathfinder is powered by a 3.5L V6 engine (284 hp). On this V6, Bank 1 is typically the rear cylinder bank (toward the firewall), and Sensor 1 is the upstream O2 sensor before the catalytic converter.
At 4-5 years old, your Pathfinder may be experiencing early O2 sensor wear or an ongoing issue.
Symptoms
- Check engine light on
- Reduced fuel economy
- Rough cold idle
- Extended warm-up
- Emissions test failure
Common Causes
O2 Sensor Heater Element Wear
The heater element degrades from thermal cycling over time.
Connector Corrosion
Years of exposure to heat and road conditions cause corrosion.
Wiring Damage
Heat from the V6 exhaust system can damage wiring.
Blown Fuse
Check the O2 heater fuse first.
Warranty Considerations
- Bumper-to-Bumper: 3yr/36k (likely expired)
- Powertrain: 5yr/60k (may still apply)
- Federal Emissions: 8yr/80k
Contact your Nissan dealer to verify coverage.
Repair Costs
- Dealer: $200-$350
- Independent shop: $160-$300
- DIY: $60-$130 for sensor
DIY Tips
The V6's transverse mounting makes Bank 1 Sensor 1 access more challenging. May require working from below or removing engine covers.