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D40A foutcode
Posted: Wed Oct 14, 2026
by liora_zabalaz
In that case, how exactly does this code work? Please tell me how to begin resolving this. The description is vague, to put it mildly.
Much obliged.
Re: D40A foutcode
Posted: Wed Oct 14, 2026
by sterlinghj
Seems like this isn't the w123 240TD that's on your profile - pretty mysterious, actually.
Google, in any case, should be able to lead you in the correct way:
Re: D40A foutcode
Posted: Wed Oct 14, 2026
by liora_zabalaz
No, it's a W204 diesel. Doubtful that the W123 supports ODB?
Given the novelty of the sensor, there may be a few frayed wires. Contact cleaner has been sprayed onto all of the plugs and pins. We'll find out if Mercedes can locate it!
Re: D40A foutcode
Posted: Wed Oct 14, 2026
by liora_zabalaz
Re: D40A foutcode
Posted: Wed Oct 14, 2026
by sterlinghj
Not at all, in my opinion. I simply wanted to point out that you didn't specify the vehicle at all, and your profile solely refers to the W123.
Re: D40A foutcode
Posted: Wed Oct 14, 2026
by sterlinghj
hat is unquestionably the reason. I thought I read somewhere that the sensors are really delicate; if that's the case, it could have been broken during installation (or, even worse, defective to begin with).
Re: D40A foutcode
Posted: Wed Oct 14, 2026
by liora_zabalaz
My bad—my profile has been updated!
Next week, I'll have Mercedes take a look.
