With Generic Scan Tool (GST)
The output of data relevant to OBD from the control modules was stipulated by law for the USA. It is described in SAE J 1979.
Data output is subdivided into different modes.
Mode 1
Output of:
- Input signals
- Output signals
- System status information
- Values calculated by the control module
Mode 2
Output of operating conditions (freeze frame) when a fault is stored in the memory.
Mode 3
(Output of stored faults. 0)
Mode 4
Erase fault memory.
Mode 5
Output of oxygen sensor data.
Mode 6
Output of test results of non-continuous tests.
Mode 7
Output of test results of continuous tests.
(Output of suspected faults)
The data sets in the modes are referred to as Parameter Identification (PID).
After being stimulated by a generic scan tool, all systems relevant to OBD log on with their address. In the 911 Carrera (996), this is the DME with the address $17 and in Tiptronic vehicles it is the transmission control module with the address $1A.
NOTE: The $ symbol means that a hexadecimal number is involved.
When the control module gives out data, it also states the mode, the PID number and the address of the control module.
Example
Mode 41Pid$01 Adr$17
Engine management
No. of faults: 0
MIL commanded OFF
Data output takes place with Mode 41 in Mode 1,
with Mode 42 in Mode 2,
with Mode 43 in Mode 3
etc.
Mode 1
The following PID's are supported in Mode 1:
$00 Supported PID's
The PID's supported in this mode are displayed in a 4- byte word (Data A, B, C and D).
Data A
PID D1 to 08:
Data B
PID 09 to 10:
Data C
PID 11 to 18:
Data D
PID 19 to 20:
0 - PID number not supported.
1 - PID number supported.
$01 Status of diagnostic system
The system status is displayed in a 4-byte word (Data A, B, C and D).
Mode 41Pid$01 Adr$17
Engine management
No. of faults: 1
MIL commanded ON
- Number of faults stored in this control module.
- Status of Check Engine Malfunction Indicator Light (MIL).
NOTE: When several control modules are involved, the status of the Check Engine MIL allows the user to determine which control module was responsible for the MIL being switched on
These data can also be designated as Data A and displayed as follows:
Data A
Bits 0 to 6
No. of faults in binary format
Bit 7
0 - Check Engine MIL was not switched on by this control module.
1 - Check Engine MIL was switched on by this control module.
Data B: 0000111
C: 01101101
D: 01101101
Data B
Data byte B displays all the sub-systems which are monitored continuously, i.e. at least twice per second.
Bit 0 - Misfire detection
Bit 1 - Fuel system
Bit 2 - Other components
Bit 3 - Not used
Bit 4 - Not used
Bit 5 - Not used
Bit 6 - Not used
Bit 7 - Not used
0 - System not supported.
1 - System supported.
Data C
Data byte C displays the sub-systems which are monitored at least once per trip.
Bit 0 - TWC
Bit 1 - TWC heating
Bit 2 - Fuel tank ventilation
Bit 3 - Secondary air system
Bit 4 - A/C system
Bit 5 - Oxygen sensor
Bit 6 - Oxygen sensor heating
Bit 7 - Exhaust gas circulation
0 - Sub-system not available.
1 - Sub-system available.
Data D
In data byte D, the readiness codes of the sub-systems from data byte C are
displayed.
Bits 0 to 7
0 - Sub-system check OK or sub-system not installed.
1 - Sub-system check not yet complete.
NOTE: After the fault memory has been erased, the bits of the installed sub-systems are set to 1. The bits are reset to 0 when the diagnostic routines are successfully performed during two trips.
$03 Status of injection system
Mode 41Pid$03 Adr$17
Data A Data B
00000010 00000010
Data A - Status of bank 1
Data B - Status of bank 2
Bit 0 - Open-loop control, the conditions for closed-loop oxygen sensing have not yet been satisfied.
Bit 1 - Closed-loop control, the signal from the oxygen sensor is used to control injection.
Bit 2 - Open-loop control through conditions such as full load, etc.
Bit 3 - Open-loop control through faults in the system.
Bit 4 - Closed-loop control, but faults from at least one oxygen sensor.
Bits 5 to 7 not used.
NOTE: Only one bit at a time can be set to 1 to indicate the status.
$04 Calculated load value
Mode 41pid$04 Adr$17
Cab. load value
6.2%
Display between 0% and 100%.
$05 Cylinder head temperature
Mode 41pid$05 Adr$17
Temperature
27°C
Display between -40 °C and 215 °C.
$06 HO2S integrator, bank 1
Mode 41pid$06 Adr$17
HO2S integrate B1
0.0%
Display: lean to -100%
rich to 99.22%
$07 HO2S adaptation, bank 1
Mode 41pid$07 Adr$17
H02S adapt. B1
0.0%
Display: lean to -100%
rich to 99.22%
$08 HO2S integrator, bank 2
Mode 41pid$08 Adr$17
HO2S integrate B2
0.0%
Display: lean to -100%
rich to 99.22%
$09 HO2S adaptation, bank 2
Mode 41pid$09 Adr$l7
HO2S adapt. B2
0.7%
Display: lean to -100%
rich to 99.22%
$OC Engine speed
Mode 41pid$00 Adr$17
Engine speed
800 rpm
Display of engine speed in rpm.
$OD Vehicle speed
Mode 41pid$OD Adr$17
Vehicle speed 0 km/h
Display of vehicle speed in km/h up to max. 255 km/h (159 mph).
$OE Ignition timing, cylinder 1
Mode 41pid$0E Adr$l7
Ignition angle 23.5°
Display: after TDC up to -64 °CA
before TDC up to 63.5 °CA
°CA - degrees crank angle
$OF Intake air temperature
Mode 41Pid$0F Adr$17
Intake air temp
32 °C
Display between -40 °C and 215 °C.
$10 Air mass
Mode 41Pid$10 Adr$17
Air mass
27.76g/s
Display between 0 and 655.35 g/s
g/s - Grams per second
$11 Throttle valve position
Mode 41pid$11 Adr$17
Throttle V. pos.
0.0%
Display between 0% and 75%
$12 Status of secondary air system
Mode 41Pid$12 Adr$17
Sec.air stat.
00000100
Bit 0 - Secondary air is injected above the first TWC.
Bit 1 - Secondary air is injected below the first TWC junction.
Bit 2 - Secondary air pump is switched off.
Bits 3 to 7 not used.
NOTE: Only one bit at a time can be set to 1 to indicate the status.
$13 Number of oxygen sensors
Mode 41Pid$13 Adr$17
00110011
Bit 0 - Bank 1, sensor 1
Bit 1 - Bank 1, sensor 2
Bit 2 - Bank 1, sensor 3
Bit 3 - Bank 1, sensor 4
Bit 4 - Bank 2, sensor 1
Bit 5 - Bank 2, sensor 2
Bit 6 - Bank 2, sensor 3
Bit 7 - Bank 2, sensor 4
0 - Sensor not available.
1 - Sensor available.
$14 Oxygen sensor signal, bank 1, sensor 1
Mode 41Pid$14 Adr$17
B1 - S1 0.44 V
0%
Display of oxygen sensor voltage and associated oxygen sensor.
Display of sensor voltage between 0 V and 1.275 V and of the oxygen sensor in percent.
Display: lean to -100%
rich to 99.22%
$15 Oxygen sensor signal, bank 1, sensor 2
Mode 41Pid$15 Adr$17
B1 - S2
0.43 V 99%
Display of oxygen sensor voltage and associated oxygen sensor.
Display of sensor voltage between 0 V and 1.275 V and of the oxygen sensor in percent.
Display: lean to -100%
rich to 99.22%
$18 Oxygen sensor signal, bank 2, sensor 1
Mode 41Pid$18 Adr$17
B2 - S1 0.43 V
0%
Display of oxygen sensor voltage and associated oxygen sensor.
Display of sensor voltage between 0 V and 1.275 V and of the oxygen sensor in percent.
Display: lean to -100%
rich to 99.22%
$19 Oxygen sensor signal, bank 2, sensor 2
Mode 41Pid$19 Adr$17
B2 - S2
0.43 V 99%
Display of oxygen sensor voltage and associated oxygen sensor.
Display of sensor voltage between 0 V and 1.275 V and of the oxygen sensor in percent.
Display: lean to -100%
rich to 99.22%
$1C OBD requirements
Mode 41Pid$1C Adr$17
01
Display of system classification.
01 - OBD II for California
02 - OBD for EPA
03 - OBD for California and EPA
04 - OBD I
05 - Does not comply with any OBD requirements
Mode 2
The following PID's are supported in Mode 2:
$00 Supported PID's
The PID's supported in this mode are displayed in a 4 - byte word.
Data A
Data B
Data C
Data D
NOTE: If there is a fault not all supported PID's are stored in the memory, but only 6.
The Data A and B bytes indicate that PID's 02, 037 04, 05, 06, 07, 08, 09, 0C and 0D are supported. From these supported PID's, the 6 most meaningful ones are stored for one fault.
$02 Diagnostic Trouble Code
The Diagnostic Trouble Code which caused the storage of freeze frame data is
displayed.
$03 Status of injection system
Mode 42Pid$03 Adr$17
Data A Data B
00001000 00001000
Data A - Status of bank 1
Data B - Status of bank 2
Bit 0 -Open loop control, the conditions for closed-loop oxygen sensing have not yet been satisfied.
Bit 1 - Closed-loop control, the signal from the oxygen sensor is used to control injection.
Bit 2 - Open loop control through conditions such as full load, etc.
Bit 3 - Open-loop control through faults in the system.
Bit 4 - Closed-loop control, but faults from at least one oxygen sensor
Bits 5 to 7 not used.
NOTE: Only one bit at a time can be set to 1 to indicate the status.
$04 Calculated load value
Mode 42Pid$04 Adr$17
Calc. load value
1.9%
Display between 0% and 100%.
$05 Cylinder head temperature
Mode 42Pid$05 Adr$17
Temperature
93 °C
Display between -40 °C and 215 °C.
$06 HO2S integrator, bank 1
Mode 42Pid$06 Adr$17
H02S integrate B1
0. 0%
Display: lean to -100%
rich to 99.22%
$07 HO2S adaptation, bank 1
Mode 42Pid$07 Adr$17
H02S adapt. B1
7.8%
Display: lean to -100%
rich to 99.22%
$08 HO2S integrator, bank 2
Mode 42Pid$08 Adr$17
H02s integrate B2
0.0%
Display: lean to -100%
rich to 99.22%
$09 HO2S adaptation, bank 2
Mode 42Pid$09 Adr$17
HO2S adapt. B2
7.8%
Display: lean to -100%
rich to 99.22%
$0C Engine speed
Mode 42Pid$0O Adr$17
Engine speed
778rpm
Display in rpm.
$OD Vehicle speed
Mode 42Pid$OD Adr$17
Vehicle speed
50 km/h
Mode 3
The Diagnostic Trouble Codes of all faults stored in the memory are displayed in Mode 3.
Mode 4
In Mode 4, the fault memory can be erased.
NOTE: The fault memories of all systems relevant to OBD are erased.
Mode 5
The values of the last oxygen sensor test can be read out for each oxygen sensor in mode 5.
For the oxygen sensors ahead of the TWC (bank 1/2, sensor 1), the following PID's are supported:
$01 Rich-lean threshold voltage
Mode 45Pid$01 Adr$17
R.toL. Sen.Volt
B1 - S1 0.440 V
Programmed fixed value.
$02 Lean-rich threshold voltage
Mode 45Pid$02 Adr$17
L. toR. Sen. Volt
B1 - S1 0.440 V
Programmed fixed value.
$07 Minimum voltage of oxygen sensor during the test
Mode 45Pid$07 Adr$17
Min. Voltage
Spec. 0.002: 0.395 V
B1 - S1 0.010 V
The specified range within which the voltage must lie and the actual value are displayed.
$08 Maximum voltage of oxygen sensor during the test
Mode 45Pid$08 Adr$17
Min. Voltage
Spec.: 0.495: 0.945 V
B1 - S1 0.830 V
The specified range within which the voltage must lie and the actual value are displayed.
$09 Time between two transitions
Mode 45Pid$09 Adr$17
Time between
Spec. 0.20: 1.20 sec
B1 - S1 0.40 sec
The specified range within which the time must lie and the actual value are displayed.
A - Sensor OK.
B - Shift in sensor characteristic e.g. due to silicon.
C - Shift in sensor characteristic e.g. due to lead.
D1 - Amount by which the characteristic has shifted towards lean (PID 31).
D2 - Amount by which the characteristic has shifted towards rich (PID 30).
$30 Shift in oxygen sensor characteristic towards rich
Mode 45Pid$30 Adr$17
< 10.2 sec
Spec.: 0.00: 1.20 sec
B1 - 51 0.00 sec
The specified range within which the time must lie and the actual value are displayed.
$31 Shift in oxygen sensor characteristic towards lean
Mode 45Pid$31 Adr$17
< 10.2 sec
Spec.: 0.00: 1.20 sec
B1 -S1 0.00 sec
The specified range within which the time must lie and the actual value are displayed.
$32 Averaged period
Mode 45Pid$32 Adr$17
< 10.2 sec
Spec.: 0.00: 4.00 sec
B1 - S1 1.80 sec
The specified range within which the time must lie and the actual value are displayed.
For the oxygen sensors after the TWC (bank 1/2, sensor 2), the following PID's are supported:
$01 Rich-lean threshold voltage
Mode 45Pid$01 Adr$17
R. toL. Sen. Volt
B1 - S
0.440 V
Programmed fixed value.
$02 Lean-rich threshold voltage
Mode 45Pid$02 Adr$17
L. taR. Sen.Volt
B1 - S2 0.440 V
Programmed fixed value.
Mode 6
The test results of components or systems which are not continuously monitored are displayed in mode 6. At the same time, limit values are provided. The test results are referred to as TID (Test Identification). The components or systems are distinguished by CID's (Component Identification).
The following components or systems are supported:
TWC conversion, bank 1
TID $01 CID $01
TWC conversion, bank 2
TID $01 CID $02
Secondary air system, bank 1
TID $03 CID $03
Secondary air system, bank 2
TID $03 CID $04
Secondary air system, bank 1
TID $03 CID $05
Secondary air system, bank 2
TID $03 CID $06
NOTE: If the DME has performed active diagnosis, then CID's $03 and $04 are displayed.
If, however, diagnosis was passive, then CID's $05 and $06 are displayed.
EVAP canister purge valve
TID $05 CID $0A
EVAP canister shutoff valve
TID $05 CID $0B
Fuel tank ventilation system (major leak)
TID $05 CID $OC
Fuel tank ventilation system (micro-leak)
TID $05 CID $0D
EVAP canister shutoff valve
TID $05 CID $11
Fuel tank ventilation system
TID $05 CID $12
Fuel tank ventilation system
TID $05 CID $13
Fuel tank ventilation system
TID $05 CID $14
Mode 7
The Diagnostic Trouble Codes of all suspected (not shedded) faults stored in the memory are displayed in Mode 7.
This mode has the same structure as Mode 3.