What Are Trouble Codes; Trouble Code Structure; Stored Trouble Codes; Pending Code - Bosch OBD 150 Manual Original

4.5

What are trouble codes

The OBD trouble codes (DTC) are defined in
SAE J2012 and ISO 15031-6. Manufacturer-spe-
cific trouble codes can be defined by vehicle
manufacturers.
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.
i
A plain language text outlining the cause of
the problem can be assigned to each trouble
code.
4.5.1

Trouble code structure

i
The structure of the trouble codes is shown in
the following table. This information facilitates
trouble-shooting in situations for which no
trouble code description is provided.
Trouble codes are 5-position codes.
Example:
P 0 1 22 Throttle position sensor signal too low
Pos. Value Description
1 B Body
C Chassis
P Powertrain
U Network
2 0, 2 Trouble code defined by ISO / SAE
Example 1 Trouble code defined by
for P manufacturer
3 Trouble code defined by ISO / SAE
or by manufacturer
3 0 – F Grouped by systems
Example 0 – 2 Fuel air metering
for P0 3 Ignition system
4 Auxiliary emission controls
5 Vehicle speed and idle control
6 Computer and output signals
7 – 9 Transmission
A – C Hybrid
D – F Reserved for ISO / SAE
4, 5 00 – 99 Identification of individual
components
Tab. 3: Trouble code structure
Robert Bosch GmbH
All you need to know about OBD | OBD 150 | 31
4.5.2

Stored trouble codes

Stored trouble codes (DTC) are trouble codes
which have been stored in the electronic con-
trol unit (ECU). The description of the trouble
code and the number of the electronic control
unit with the designation of its origin are also
displayed.
i
If a trouble code has been set which causes
the malfunction indicator light (MIL) to come
on, the electronic control unit stores the
current values of the sensors at the time at
which the fault occurred.
4.5.3

Pending code

The first time a fault occurs this is stored as a
pending code in the fault memory. If a pending
code is confirmed in the second drive cycle,
it becomes a confirmed code. A pending code
stored in the electronic control unit is automati-
cally erased after 40 drive cycles if the prevailing
operating conditions were the same as when
the trouble code was set. Otherwise the pend-
ing code is erased after 80 engine cycles. Such
trouble codes report those faults which have
occurred during a drive cycle but which were
not sufficient to cause a trouble code to be
stored, i.e. not causing the malfunction indicator
light to come on.
4.5.4

Confirmed code

If a pending code is confirmed in the second
drive cycle, it becomes a confirmed code and
the malfunction indicator light comes on.
4.5.5

Permanent code

Permanent codes are a special form of confirmed
codes. Permanent codes have only been set by
vehicles since 2010, which means that they are
not supported by all vehicles.
i
Permanent codes cannot be erased with a di-
agnostic tester or by disconnecting the battery
voltage. The problem must have been rectified
and must not have occurred again for the trou-
ble code to be automatically deleted from the
fault memory by the electronic control unit.
i
The presence of a permanent code will cause
the vehicle to fail an Inspection or exhaust
emission test.
569630 Rev "D"
en
|
2016-02-19