P0135 – Audi DTC

Audi DTC P0135 – Defective Oxygen Sensor/Air Fuel Ratio Sensor, defective Oxygen Sensor/Air Fuel Ratio Sensor Heater Circuit, Exhaust System Leak, Intake Air System leak, Low Fuel Pressure, Defective Engine Coolant Temperature Sensor, Defective sensor wiring and/or circuit problem, PCM software needs to be updated, Defective PCM

DTC P0135 meaning on Audi

DTC P0135 refers to a malfunction in the oxygen sensor or air-fuel ratio sensor heater circuit in Audi vehicles. This code indicates that the Engine Control Module (ECM) has detected a problem with the heater circuit of the oxygen sensor, which is crucial for maintaining optimal engine performance and emissions control.

Audi DTC P0135 symptoms

Common symptoms associated with DTC P0135 may include:

• Check Engine Light illuminated
• Poor fuel economy
• Rough engine idle
• Increased emissions
• Failed emissions test

Audi DTC P0135 causes

Several factors can lead to the triggering of DTC P0135, including:

• Defective oxygen sensor or air-fuel ratio sensor
• Defective oxygen sensor or air-fuel ratio sensor heater circuit
• Exhaust system leak
• Intake air system leak
• Low fuel pressure
• Defective engine coolant temperature sensor
• Defective sensor wiring and/or circuit problem
• PCM software needs to be updated
• Defective PCM

Audi DTC P0135 seriousness

DTC P0135 is considered serious as it can lead to:

• Increased emissions, which can harm the environment
• Poor engine performance and fuel efficiency
• Potential damage to the catalytic converter
• Failure to pass emissions testing

How to diagnose DTC P0135 on Audi

To diagnose DTC P0135, follow these steps:

1. Use an OBD-II scanner to confirm the DTC and check for any additional codes.
2. Inspect the oxygen sensor and its wiring for any visible damage or corrosion.
3. Check the heater circuit for continuity and proper voltage.
4. Examine the exhaust and intake systems for leaks.
5. Test the engine coolant temperature sensor for proper operation.
6. Verify fuel pressure to ensure it meets specifications.
7. Consider updating the PCM software if necessary.

How to fix DTC P0135 on Audi step-by-step instructions

To fix DTC P0135, follow these steps:

1. Replace the defective oxygen sensor or air-fuel ratio sensor if found faulty.
2. Repair or replace any damaged wiring or connectors in the heater circuit.
3. Seal any exhaust or intake leaks identified during diagnosis.
4. Replace the engine coolant temperature sensor if it is defective.
5. Ensure fuel pressure is within the manufacturer’s specifications replace the fuel pump if necessary.
6. Update the PCM software if applicable.
7. Clear the DTC using an OBD-II scanner and test drive the vehicle to ensure the issue is resolved.

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