Glossary - Bosch OBD 150 Manual Original

en 44 | OBD 150 | Glossary
8.

Glossary

CAN Controller Area Network
The CAN bus is used for serial data transfer in
motor vehicles.
Confirmed code
If a pending code is confirmed in the second
drive cycle, it becomes a confirmed code and
the malfunction indicator light (MIL) comes on.
CVN Calibration Verification Number
DTC Diagnostic trouble code
A trouble code is a 5-position code made up of a
letter and four digits. A distinction is made be-
tween standard trouble codes which may occur
with all vehicle makes and manufacturer-specific
trouble codes specified by vehicle manufactur-
ers for certain vehicle models. A plain language
text outlining the cause of the problem can be
assigned to each trouble code.
ECU Electronic control unit
EOBD European On-Board diagnosis
EOBD is not an official term but is often used to
refer to OBD-2 in conjunction with EU vehicles.
For further information refer to Section 4.1.
Drive cycle
A drive cycle commences on starting the engine
(warm or cold) and ends on switching off the
engine.
Freeze frame data (FFD)
The following data (freeze frame data) are
stored in connection with the first pending
code:
R
Vehicle speed
R
Coolant temperature
R
Intake manifold pressure
R
Engine load
R
Mixture formation adaptation value
R
Lambda control status (control loop)
R
Time since trouble first recorded
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569630 Rev "D" 2016-02-19
The data represent a sort of snapshot of the pre-
vailing operating and ambient conditions at the
moment in time at which the trouble was detect-
ed. A freeze frame data set remains stored in the
memory even if another emission-related trouble
code is stored (this does not however apply to
trouble codes resulting from misfiring or faults
in the fuel system). Freeze frame data stored for
a trouble code arising from misfiring or a fuel
system fault overwrite all previously stored data
and cannot be overwritten themselves.
I/M monitors
The Readiness code is used in OBD to refer to
the testing of emission-related functions. Since
the introduction of OBD-2 all electrical compo-
nents have been continuously checked for prop-
er operation. In addition, complete systems (e.g.
exhaust gas recirculation) are checked by way
of diagnostic routines which are not constantly
active. The Readiness code is set as a means of
checking whether these diagnostic routines have
been performed.
The Readiness code gives an indication of
whether a diagnosis result has been supplied
for all individual systems since the fault memory
was last erased or the electronic control unit
was replaced.
The following are permanently monitored:
R
Missing combustion
R
Fuel system (injection times)
R
Circuits for emission-related components
The following are monitored once per drive
cycle:
R
Lambda sensor function
R
Catalytic converter function
If the functions of systems and components
are tied to certain operating conditions, these
are only checked on passing the corresponding
operating points (speed, load or temperature
thresholds).
i
The Readiness code was introduced as a
means of revealing manipulation. It makes
it possible to see whether the fault memory
was erased by disconnecting the battery for
example.
Robert Bosch GmbH