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GAP Diagnostic 2023-09-12 All Rights Reserved
User Manual G3 units : Version 37, Firmware V4.0
1
st
Fault Code
Element
1
st
character. Systems on
which the fault is present.
3
rd
character. Subsystem*
Pxxxx
P for Powertrain
1= Air/Fuel ratio
2= Fuel injection
3= Ignition and misfire
4= Emission control
5= Engine speed and idle speed
6= ECU and output circuits
7, 8 and 9= Transmission
A,B and C=Hybrid system
Cxxxx
C for Chassis
Bxxxx
B for Body or Accessories
Uxxxx
U for Communication network
Table 19.
1
st
element interpretation
*Some manufacturer specific codes do not follow this nomenclature.
Conclusions on the interpretation of the
1
st
fault code element
When the 1
st
element begins with a P,C or B = generally precise information pointing directly to the
origin of the appearance of the fault.
When the 1
st
element begins with a U = typically occurs as a result of the appearance of faults on ano
-
ther system (starting with P, C, B). May indicate a “consecutive” fault causing a “cascading effect”. Ge
-
nerated by a loss of communication or reception of invalid data sent by the ECU creating the cascade.
Note that the interpretation of consecutive type faults obtained as a result of a cascade effect can be
challenging (diagnostic procedure in case of cascading effect
If faults with a “lost communication with ...” definition are still present and that there are no other
symptoms observed, they can be ignored. These faults are recorded from time to time for no apparent
reason. If faults with the U prefix and unrelated to a communication error are, simply correct the issues
and use the clear fault function.
