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      12-29-2012, 03:52 PM   #1
aerobod
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Drives: Caterham R500, M2-G87, Macan S
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5e40 Fault Code & relationship to battery failure

An interesting bit of information I just deduced from resetting my steering angle sensor. Fault code 5e40 in the DSC/ABS module has a dual meaning. From a diagnostics perspective with my Bavarian Technic tool the initial error shown is "5e40 - Wheel speed sensor rear right: Signal edge missing(RDF-Typ11i).", which would point to a failing wheel sensor. An alternate description is "5e40 - Lateral acceleration signal not plausible, Offset ", this would indicate a mis-match between the steering (yaw) sensor and the perceived lateral acceleration, i.e. the steering angle sensor needs to be aligned.

So, if you have an indication from your diagnosis software that you have a rear right wheel sensor failing, it may just be a quick calibration of the steering angle sensor that is required.

From a battery failure providing a low voltage perspective, I noticed that 5e40 and various SRS codes and General Module codes were set in the fault memory. I'm not sure how the software code is written, but either a 5e40 fault code is first to be set when the module is in distress due to low voltage, or it may just be a coincidence with my car. This does explain to me why you see a general DSC/ABS failure as a symptom of a failing battery, as this error will set the ABS, DSC off and Brake Warning light yellow, as the DSC/ABS module seems to be more voltage sensitive than others.
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