P0056

P0056

Oxygen Sensor Heating Output Stage After TWC, Bank 2 - Open Circuit

Diagnosis conditions
- Battery positive voltage between 10 V and 16 V
- Time elapsed after engine start-up greater than 10 seconds

Possible fault cause
- FE18 fuse faulty (fuse carrier in E-box, radiator tank)
- Loose contact in connector
- Break in wiring in voltage supply of oxygen sensor heating
- Break in wiring in connection to ground of oxygen sensor heating
- Oxygen sensor heating faulty (heating resistance too high)
- DME control module faulty

Affected pin
DME control module connector A, pin 6, and oxygen sensor connector after TWC, bank 2, pin 2

Diagnosis/troubleshooting
- Do not use contact spray on the oxygen sensor plug connections, as this may cause irreparable damage to the wiring (blocking the reference air channels).
- Do not confuse oxygen sensor ahead of catalytic converter and oxygen sensor after catalytic converter as this will cause implausible fault entries.

Distinguishing feature of both sensors:







Oxygen sensor ahead of catalytic converter (LSU) has a 6-pole connector







Oxygen sensor after catalytic converter (LSF) has a 4-pole connector

- If connector A is disconnected from the DME control module and the ignition is or was switched on, the 'DME Control Module TIMEOUT' fault is recorded in many control modules.
- If control module connector A was disconnected from the DME in the course of troubleshooting or if the voltage supply was interrupted elsewhere (battery, fuse), the throttle adjusting unit must be adapted.