Emissions

P00D6 — Bank 2 O2 Sensor 1 / Sensor 2 Correlation Fault

Severity: low Safe to drive

What P00D6 means

The engine control module compares the signal from the Bank 2 upstream heated oxygen sensor (sensor 1) with the downstream sensor (sensor 2) behind the catalytic converter. Normally the upstream sensor switches rapidly between rich and lean, while the downstream one stays steadier. When the two signals don't match what the ECM expects, it sets P00D6 and turns on the check engine light.

Symptoms

  • Check engine light on
  • Reduced fuel economy
  • Rough or unstable idle (not always)
  • Failed emissions test
  • Occasional drop in performance

Possible causes

  1. Failed or aged Bank 2 oxygen sensor (sensor 1 or sensor 2)
  2. Sensor contaminated by soot, oil, coolant or silicone
  3. Exhaust leak on Bank 2 near the sensors
  4. Damaged wiring or poor connector contact at the sensors
  5. Sensor heater circuit fault
  6. Mixture problem on Bank 2 (injector, vacuum leak, fuel pressure)
  7. Worn Bank 2 catalytic converter
  8. Rarely, an ECM fault

How to diagnose

  1. Scan all codes and freeze frame data, looking for related misfire, fuel trim or heater circuit codes
  2. Inspect Bank 2 sensor wiring and connectors for damage, corrosion, chafing or heat damage
  3. Check the Bank 2 exhaust for leaks before and around the sensors
  4. View live data for Bank 2 sensors 1 and 2, including heater status
  5. Compare Bank 2 short and long term fuel trims with Bank 1
  6. Test heater circuit resistance and the sensor connector's power and ground with a multimeter
  7. Rule out rich or lean causes such as vacuum leaks, injectors and fuel pressure
  8. Judge catalytic converter condition from the downstream sensor response

Common fixes

  • Replace the faulty Bank 2 oxygen sensor
  • Repair the exhaust leak
  • Repair damaged wiring or replace the connector
  • Correct the cause of the mixture problem (vacuum leak, injector, etc.)
  • Replace the catalytic converter if it is confirmed bad

Questions and answers

What does P00D6 mean?

The ECM found that the oxygen sensor readings before and after the catalytic converter on Bank 2 don't agree. The cause may be the sensors, wiring, exhaust or the air-fuel mixture.

Can I drive with P00D6?

Usually yes for a short time. Don't put it off, though: poor mixture control raises fuel use and can eventually damage the catalytic converter.

Should I replace the oxygen sensor right away?

No. First check the wiring, connectors, exhaust leaks and fuel trims. Replace the sensor once those are ruled out or scan data shows it is faulty.

This is general information about the code. The meaning can differ between makes and models: a scan tool and the repair manual for your car will show the exact cause.