P013B

What it means

P013B means the engine control unit has judged that the downstream oxygen sensor (Bank 1 Sensor 2, after the catalytic converter) is responding too slowly when the exhaust mixture changes from lean to rich. The ECU watches how quickly the sensor voltage or signal switches during a lean-to-rich transition, usually during fuel control changes, and sets the code when the response time is longer than expected. The fault points to a slow or degraded sensor, but exhaust leaks, contamination or fuelling problems can also cause it.

Symptoms

• Engine warning light on
• Usually no noticeable change in driving
• Possible slight increase in fuel consumption
• Possible rough running or hesitation if a fuelling fault is also present
• Failed emissions test or poor emissions readings

Possible causes

• Ageing or contaminated downstream oxygen sensor (Bank 1 Sensor 2) with slow responselikely
• Exhaust leak near the sensor or upstream of it letting in false airpossible
• Damaged wiring, poor connector contact or corrosion in the sensor circuitpossible
• Sensor contaminated by oil, coolant, silicone or fuel additivespossible
• Underlying fuelling fault such as a lean or rich condition, or a problem with the upstream sensorpossible
• Degraded catalytic converter affecting the downstream sensor signalrare
• Sensor heater circuit fault causing the sensor to run too coolrare

How to diagnose

1. Read all stored and pending codes and note any fuel trim, misfire, heater or upstream sensor codes, which should be diagnosed first
2. Review freeze frame data to see engine load, temperature and speed when the fault set
3. Inspect the Bank 1 Sensor 2 wiring and connector for damage, heat contact, water ingress and corrosion
4. Check the exhaust for leaks around the manifold, catalytic converter joints and the sensor mounting
5. Check short and long term fuel trims at idle and at about 2500 rpm for signs of a lean or rich fault
6. Watch the live downstream sensor signal as the engine moves from lean to rich, for example with a brief throttle snap, and compare it with the expected behaviour for that model
7. Check the sensor heater circuit supply, earth and resistance against the manufacturer's specification
8. Inspect the removed sensor tip for contamination, and look for causes such as oil or coolant consumption

How to fix

• Replace the downstream oxygen sensor if it is slow, contaminated or out of specification
• Repair or replace damaged wiring or connectors in the sensor circuit
• Repair exhaust leaks and fit new gaskets or sealing as needed
• Correct any underlying fuelling, air intake or engine problem such as oil or coolant entering the exhaust
• Replace the catalytic converter only if testing confirms it has failed and is the cause

Can I keep driving?

Nearby codes

• P013AGenericO2 Sensor Slow Response - Rich to Lean Bank 1 Sensor 2
• P013CGenericO2 Sensor Slow Response - Rich to Lean Bank 2 Sensor 2