What P0135 Means for Your 2018 Altima
Your 2018 Nissan Altima has logged a P0135 diagnostic trouble code, indicating a malfunction in the oxygen sensor heater circuit for Bank 1, Sensor 1. The 2018 Altima came with either the 2.5L four-cylinder (179 hp) or the 3.5L V6 (270 hp). The four-cylinder has a single exhaust bank, while the V6 has two banks.
At 6+ years old, your Altima is likely experiencing normal O2 sensor wear. The heater element inside the sensor degrades over time from constant thermal cycling.
Symptoms You're Experiencing
- Steady check engine light
- Reduced fuel economy (2-5% decrease)
- Rough idle during cold starts
- Longer warm-up period
- Failed emissions test
Most Altima owners find the car runs fine once warmed up. The heater element's job is to speed up warm-up time.
Common Causes on the 2018 Altima
Worn O2 Sensor Heater Element
At 80,000+ miles, heater element failure is common. The constant on-off cycling during normal driving eventually wears out the element.
Connector Corrosion
After six years of exposure to heat and road conditions, the sensor connector can develop corrosion on the heater circuit pins.
Wiring Degradation
Heat from the exhaust system can damage wiring insulation over time. Look for brittle or cracked insulation near the sensor.
Blown Fuse
A blown O2 heater fuse is a simple cause to rule out first.
Warranty Status
Your 2018 Altima's original warranty has expired:
- Bumper-to-Bumper: 3 years/36,000 miles (expired)
- Powertrain: 5 years/60,000 miles (expired)
- Federal Emissions: 8 years/80,000 miles (may still apply)
If under 80,000 miles, check with Nissan about federal emissions warranty coverage.
Diagnosis Steps
- Check emissions warranty—May still cover the repair
- Identify your engine—Affects sensor location (especially V6)
- Check fuse—Free and quick
- Inspect connector—Look for corrosion
- Test heater resistance—Should be 2-30 ohms
- Verify voltage supply—Battery voltage with key on
Repair Costs
Professional Repair
- Dealer: $180-$320
- Independent shop: $140-$280
DIY Approach
- OEM Nissan sensor: $70-$130
- Quality aftermarket: $40-$90
- O2 sensor socket: $15-$25
DIY Replacement Guide
Four-Cylinder Models
Good sensor access from above the engine. Straightforward replacement.
V6 Models
Bank 1 Sensor 1 may require more maneuvering due to the V6's transverse mounting. Access from above or below depending on configuration.
- Work with cold engine
- Apply penetrating oil overnight if sensor is seized
- Disconnect electrical connector
- Use O2 sensor socket with wire slot
- Apply anti-seize to new sensor threads
- Torque to spec (30-40 ft-lbs)
- Clear codes and test drive
Choosing a Replacement Sensor
- OEM Nissan: Best compatibility, higher price
- Denso: Often the OEM supplier for Nissan
- Bosch: Quality aftermarket option
- NTK: Another quality choice
Avoid ultra-cheap sensors that may fail quickly or cause drivability issues.
Prevention Tips
- Use Top Tier gasoline
- Address oil consumption issues promptly
- Plan for O2 sensor replacement around 100,000 miles
- Fix any exhaust leaks that may affect sensors