what causes my Toyota Corolla E170 (2013-2019) to have a check engine light with code P0135

• •Check engine light illuminated
• •Poor fuel economy
• •Engine stalling or rough idle
• •Increased emissions
• •Decreased engine performance

1. 1Scan the vehicle with an OBD-II scanner to confirm the P0135 code and check for any additional codes.
2. 2Inspect the wiring and connectors of the upstream oxygen sensor for damage, corrosion, or loose connections.
3. 3Measure the voltage output of the oxygen sensor using a multimeter while the engine is running.
4. 4Check the engine coolant temperature sensor to ensure it is functioning correctly, as it can affect oxygen sensor operation.
5. 5Inspect and test the vehicle's engine control module (ECM) for faults that may affect communication with the oxygen sensor.

After completing the repair, verify that the issue has been resolved:

• ✓Test the affected component to ensure it functions correctly
• ✓Check for any error codes or warning lights
• ✓Monitor the vehicle for a few days to ensure the issue does not recur

To prevent this issue from occurring again:

• •Follow the manufacturer's recommended maintenance schedule
• •Address warning signs early before they develop into major issues
• •Use quality parts and fluids recommended for your vehicle
• •Keep detailed records of all repairs and maintenance

• •OBD-II scanner
• •Oxygen sensor socket
• •Ratchet
• •Torque wrench
• •Multimeter
• •Wire brush
• •Safety glasses

• •New upstream oxygen sensor