Understanding P0135 in Your 2018 Ram 1500
Your 2018 Ram 1500 has triggered P0135, indicating oxygen sensor heater circuit malfunction. At 6-8 years old, sensor failures are common due to accumulated thermal cycling and contamination.
Symptoms
- Check engine light on
- Significantly reduced fuel economy
- Rough cold idle
- Hesitation during cold starts
- Reduced power when cold
- Failed emissions test
Root Causes
Failed Heater (75%)
Age-related wear after 60,000-100,000+ miles.
Damaged Wiring (15%)
Years of heat, vibration, and road salt exposure.
Blown Fuse (5%)
Electrical issues.
Poor Ground (4%)
Corrosion at ground points.
Software (1%)
Rare in 2018 models.
Diagnosis
- Scan all codes
- Thoroughly inspect aged wiring
- Test fuse, resistance, power, ground
- Check sensor for contamination
Repairs
Sensor: $150-$550
Moderate to Advanced | 60-120 min
Sensor may be seized after years of use.
Wiring: $50-$500
Fuse: $5-$100
Prevention
- Quality fuel
- Regular maintenance
- Replace both upstream sensors together if high mileage