What is a P0135 code on 1998 Nissan Maxima?

The P0135 code on a 1998 Nissan Maxima refers to a problem with the oxygen sensor circuit. Specifically, it indicates that there is a fault in the heater circuit of the upstream oxygen sensor (Sensor 1, Bank 1). The oxygen sensor is responsible for measuring the amount of oxygen in the exhaust gases, which helps the engine control module (ECM) adjust the air-fuel mixture for optimal combustion.

P0135 Code Breakdown:

• P: Powertrain (engine and transmission)
• 0: Generic code (for all manufacturers)
• 1: Sensor 1 (upstream, before the catalytic converter)
• 3: Indicates an issue with the oxygen sensor heater circuit
• 5: Heater malfunction (the specific issue)

Common Causes of P0135 Code:

1. Faulty Oxygen Sensor Heater: The heating element inside the oxygen sensor may be malfunctioning.
2. Wiring or Connector Issues: Damaged or corroded wiring or connectors in the oxygen sensor circuit can cause electrical problems.
3. Blown Fuse: The fuse that controls the oxygen sensor heater circuit might be blown.
4. Faulty ECM (Engine Control Module): In rare cases, a malfunction in the ECM could cause incorrect readings or the failure of the heater circuit.
5. Exhaust Leaks: Leaks before the oxygen sensor may lead to improper readings, triggering the code.

Symptoms:

• Check engine light (CEL) on
• Reduced fuel efficiency
• Rough idle or hesitation during acceleration
• Increased emissions

Possible Solutions:

1. Inspect the Oxygen Sensor: Check if the sensor is damaged or worn out, especially if it has been in use for many years.
2. Check Wiring and Connectors: Inspect the oxygen sensor wiring and connectors for signs of damage or corrosion.
3. Replace the Oxygen Sensor: If the sensor is faulty, it should be replaced with a new one.
4. Check the Fuse: Replace any blown fuses related to the oxygen sensor heater circuit.
5. Verify Exhaust System: Make sure there are no leaks before the oxygen sensor.

If you’re unsure about how to proceed with repairs, it may be helpful to consult a mechanic who can properly diagnose and fix the issue.

Let me know if you need more assistance! 😊