P0040 – BMW

Code : P0040
Make : BMW
Description : P0040 BMW O2 Sensor Signal Wires Swapped- HO2S11 with HO2S21
Possible causes :
– HO2S11 and HO2S21 sensors harness is open or shorted
– HO2S11 and HO2S21 sensors circuit connectors (wrong connection)
– Faulty Engine Control Module (ECM)
Solutions :
– Carry out a Reset via CarDiag
– Choose a better quality fuel
– Check that the tank cap is securely closed
– Check the oil level and add more if it is lower than MAX
– Restart an Automatic diagnostic via CarDiag
– If the fault persists, you can check the “Possible causes” listed above : visually inspect (by yourself (tutorials to come) or by a professional) the wiring harness and the associated connectors, check for damaged components, and look for broken, bent, pushed, or corroded connector pins.

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