P0135 on the 2022 Toyota Tacoma
The 2022 Toyota Tacoma runs the 1GR-FE 3.5-liter V6 engine producing 278 horsepower, and a P0135 code means the upstream O2 sensor heater circuit on Bank 1 has malfunctioned. On the Tacoma's longitudinally mounted V6, Bank 1 is the passenger side cylinder bank. The upstream sensor sits in the exhaust manifold ahead of the catalytic converter on that side. The heater element inside the sensor is essential for rapid warm-up to 600°F operating temperature.
Truck-Specific Sensor Access
The Tacoma has a body-on-frame design with the engine mounted longitudinally, which actually makes O2 sensor access better than in many crossover SUVs. Working from underneath the truck, the Bank 1 upstream sensor is accessible along the passenger-side exhaust manifold. If your Tacoma has a lift kit or larger tires, you have even more room to work underneath. However, trucks that see off-road duty may have mud, debris, or underbody damage that complicates wiring inspection.
Common Causes on the Tacoma V6
- O2 sensor heater burnout (High Likelihood): The 1GR-FE is a proven engine, and the Denso OEM sensors are durable, but heater elements are wear items. On Tacomas used for towing or hauling, higher exhaust temperatures accelerate heater coil degradation. Off-road use with engine RPMs varying widely also cycles the heater more aggressively.
- Underbody wiring damage (Medium Likelihood): Tacomas that go off-road face a higher risk of wiring damage from rocks, branches, and mud. The O2 sensor connector and harness can be damaged by trail debris. Even on street-driven Tacomas, road splash and salt exposure corrode connectors over time.
- Blown heater fuse (Medium Likelihood): The engine compartment fuse box contains the O2 heater fuse. A quick check can save hours of diagnosis. If both P0135 and P0155 codes are present, a shared fuse is the likely culprit.
- ECM ground or relay failure (Low Likelihood): The ECM controls the heater ground circuit. A failed internal driver or corroded ground connection is possible but uncommon on Toyota trucks of this age.
Diagnosis Steps
Warranty Consideration
Your 2022 Tacoma is within the 8-year/80,000-mile federal emissions warranty. O2 sensors are covered emissions components. Check with your Toyota dealer for a free repair before spending any money.
Fuse Check
Pop the hood and check the O2 heater fuse. Pull it, inspect visually, and test with a multimeter. If blown, replace it with the correct amperage fuse and clear the code.
Sensor Inspection
Raise the truck and locate the Bank 1 upstream sensor on the passenger-side exhaust manifold. If your Tacoma has been off-road, clean the sensor connector area before disconnecting to prevent contamination. Check the connector for moisture, corrosion, or physical damage. Inspect the harness for pinching or abrasion from underbody contact.
Heater Resistance Test
Disconnect the sensor and measure heater resistance. A healthy Denso sensor reads 2 to 14 ohms. Open circuit confirms a dead heater. Also verify battery voltage at the harness connector with the ignition on. On the Tacoma V6, the wiring runs along the frame rail, so check for damage along the entire length.
Repair Costs
Under warranty: free. Out of pocket: OEM Denso sensor for the 1GR-FE V6 costs $90 to $160. Shop labor is $100 to $160 depending on whether the shop uses a lift. Total professional repair: $190 to $320. DIY is straightforward on the body-on-frame Tacoma if you have access to a jack and stands. Allow about 45 minutes for the job. Use a 22mm O2 sensor socket and apply penetrating oil to the threads.
Off-Road Owners: Extra Precautions
If your Tacoma regularly sees trails, consider adding wire loom or additional heat shielding to the O2 sensor wiring after repair. Mud and water fording can push moisture into connectors, and rocks can snag wiring. Some Tacoma owners apply dielectric grease to the connector after reinstallation to prevent future moisture intrusion. Also inspect your skid plates to make sure they are not directing debris toward the sensor wiring.