P0040 O2 Sensors Upstream Interchanged

P0040

O2 sensors upstream interchanged

"Interchanged oxygen sensors" means that the sensor connected to the DME control module as a sensor for bank 1 is in reality placed in the exhaust pipe of bank 2 and vice versa.

Diagnostic conditions
- Oxygen sensing active

NOTE: In this context, please also observe the function description.

Possible fault causes
- Oxygen sensor upstream interchanged (sensor for bank 1 is in exhaust assembly of bank 2 and vice versa)
- Engine harness repaired incorrectly (cable interchanged)

Function description

O2 sensors upstream interchanged
The function detects interchanged oxygen sensors via oxygen sensing for both banks. If a fault is present, the values reaching the stop are swapped over.

Procedure of the function:
- After the oxygen sensors upstream are operational, the oxygen sensing is released. The mixture is regulated depending on the oxygen sensor values measured using the sensors for each bank.
- If the oxygen sensors upstream were interchanged, the mixture made rich would be detected on the opposite bank. The same applies to making the mixture lean.
- Since the oxygen sensors measure the mixture corrections of the opposite bank, the oxygen sensing values reaching the stop are swapped over (i.e., the upper limit value for one bank and the lower limit value for the other bank) and remain there.

"Interchanged oxygen sensors" means that the sensor connected to the DME control module as a sensor for bank 1 is in reality placed in the exhaust pipe of bank 2 and vice versa.