Understanding P0135 on Your 2020 Colorado
Your 2020 Chevrolet Colorado has triggered a P0135 diagnostic code, indicating a malfunction in the oxygen sensor heater circuit for Bank 1, Sensor 1. The 2020 Colorado offered three engine options: the 2.5L four-cylinder (200 hp), 3.6L V6 (308 hp), and 2.8L Duramax diesel. Each has different exhaust configurations and O2 sensor locations.
On the V6, Bank 1 is typically the rear cylinder bank in the transverse-ish mounting. On the four-cylinder and diesel, there's a single bank. Sensor 1 is always the upstream O2 sensor before the catalytic converter. The heater element inside this sensor needs to reach operating temperature quickly for accurate fuel control.
Symptoms You May Notice
- Check engine light on (steady)
- Slightly reduced fuel economy
- Rough idle during cold starts
- Takes longer for engine to run smoothly
- Emissions test failure
Most Colorado owners find the truck drives normally once warmed up. The heater circuit issue affects cold-start efficiency, not normal driving performance.
Common Causes on the 2020 Colorado
O2 Sensor Heater Element Wear
At 4-5 years old with potential work truck usage, the heater element may have experienced accelerated wear. The Colorado sees frequent short trips and work cycles that stress O2 sensors more than highway driving.
Connector Corrosion
Trucks often operate in harsher conditions—mud, water crossings, road salt. The O2 sensor connector can develop corrosion that affects the heater circuit.
Wiring Damage
If you use your Colorado for off-road activities, debris can damage the sensor wiring. Even road use exposes the wiring to heat and vibration over time.
Blown Fuse
A simple blown fuse can disable the heater circuit. This is a free, quick check before assuming the sensor is bad.
Warranty Considerations
Check your 2020 Colorado's warranty status:
- Bumper-to-Bumper: 3 years/36,000 miles (likely expired)
- Powertrain: 5 years/60,000 miles (may still apply)
- Federal Emissions: 8 years/80,000 miles for certain components
Contact your Chevrolet dealer to verify emissions warranty coverage before paying for repairs.
Diagnosis Steps
- Check warranty—Could save money
- Identify your engine—Determines sensor location
- Check fuse—Free and quick
- Inspect connector—Look for corrosion or damage
- 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: $150-$280
- Diesel specialist (if applicable): $200-$350
DIY Approach
- OEM AC Delco sensor: $70-$130
- Quality aftermarket: $50-$100
- O2 sensor socket: $15-$25
DIY Replacement Tips
Sensor accessibility varies by engine:
- 2.5L I4: Good access from above
- 3.6L V6: Bank 1 Sensor 1 may require reaching behind engine
- 2.8L Diesel: Different exhaust layout, check service manual
- Work with a cold engine
- Apply penetrating oil to sensor threads overnight
- Disconnect electrical connector
- Use O2 sensor socket with wire slot
- May need extensions and universal joints
- Apply anti-seize to new sensor threads
- Torque to spec (30-40 ft-lbs)
- Clear codes and test drive
Work Truck Considerations
If your Colorado is used for work purposes with frequent short trips, idling, or hauling, O2 sensors may wear faster than in passenger vehicle use. Budget for sensor replacement as part of your maintenance schedule, typically around 80,000-100,000 miles or sooner under heavy use.
Prevention Tips
- Use quality fuel from reputable stations
- Let engine warm up before heavy loads
- Address oil leaks promptly
- Rinse undercarriage after off-road use