Data Output With a Scan Tool

Data Output With A Scan Tool - 911 Carrera (996)
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), if a fault has been stored.

Mode 3
Output of stored faults.

Mode 4
Erase the 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 vehicles with ME 7.8, this is the DME with the address $11 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 provides data, it also states the mode, the PID number and the address of the control module

For example:
Mode 41 PID $01 address $11

Engine control
Number of faults: 0
Check Engine: off

The output of data is carried out:
in Mode 1 with Mode 41,
in Mode 2 with Mode 42,
in Mode 3 with Mode 43, etc.

Mode 8
Activation of drive links (is not supported)

Mode 9
Output of vehicle information (as of model year 2002)

Mode 1
The following PIDs are supported:

$00 Supported PIDs
The PIDs supported in this mode are output.

$01 Status of diagnostic system
The system status is output in a 4-byte word (Data A, B1 C and D).

For example:

Data
A: 1000 0001
B: 0000 0111
C: 0110 1101
D: 0110 1101

Data A

Bits 0 to 6
Number 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

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 driving cycle

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 completed 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
- in the case of a fault-free check after 1 driving cycle
- in the case of a detected fault after 2 driving cycles

$03 Status of injection system

Data
A: 0000 0010
B: 0000 0010

Data A - Status for bank 1
Data B - Status for bank 2

Bit 0 Secondary air is injected ahead of the TWC.
Bit 1 Not used
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
Output of the number and location of oxygen sensors.

Bit 0 Bank 1, sensor 1 (ahead of TWC, cylinders 1 - 3)
Bit 1 Bank 1, sensor 2 (after TWC, cylinders 1 - 3)
Bit 2 Bank 1, sensor 3 not installed
Bit 3 Bank 1, sensor 4 not installed
Bit 4 Bank 2, sensor 1 (ahead of TWC, cylinders 4 - 6)
Bit 5 Bank 2, sensor 2 (after TWC, cylinders 4 - 6)
Bit 6 Bank 2, sensor 3 not installed
Bit 7 Bank 2, sensor 4 not installed

0 - Sensor not available.
1 - Sensor available.

$14 Oxygen sensor signal, bank 1, sensor 1
Output 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.
In the case of decimal output, conversion factor = 0.005 (voltage of oxygen sensor)
Decimal value displayed multiplied by 0.005 gives the voltage of oxygen sensor.

Oxygen sensor display:
Lean to -100%
Rich to 99.22%

In the case of decimal output, conversion factor = 0.78125

Offset = -100 %

Decimal value displayed multiplied by 0.78125 minus 100% gives the HO2S integrator.

$15 Oxygen sensor signal, bank 1, sensor 2
Output 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.
In the case of decimal output, conversion factor = 0.005
Decimal value displayed multiplied by 0.005 gives the voltage of oxygen sensor.

NOTE: Since the sensor behind the catalytic converter is not included in the closed-loop control, no value for the oxygen sensor is displayed.

$18 Oxygen sensor signal, bank 2, sensor 1
Output 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.
In the case of decimal output, conversion factor = 0.005
Decimal value displayed multiplied by 0.005 gives the voltage of oxygen sensor (voltage of oxygen sensor)
Decimal value displayed multiplied by 0.005 gives the voltage of oxygen sensor.

Oxygen sensor display:
Lean to -100%
Rich to 99.22%

In the case of decimal output, conversion factor = 0.78125

Offset = -100 %

Decimal value displayed multiplied by 0.78125 minus 100% gives the HO2S integrator.

$19 Oxygen sensor signal, bank 2, sensor 2
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.
In the case of decimal output, conversion factor = 0.005
Decimal value displayed multiplied by 0.005 gives the voltage of oxygen sensor.

NOTE: Since the sensor behind the catalytic converter is not included in the closed-loop control, no value for the oxygen sensor is displayed.

$1C OBD requirements
Output of system classification.

01 OBD II for California
02 OBD for EPA
03 OBD II for California and EPA
04 OBD I
05 Fulfills no OBD requirements
06 EOBD (European OBD)

Mode 2
In mode 2 the operating conditions (freeze frame data) at the time of fault entry are output The operating conditions of the fault which occurred first are stored.

If a fuel system fault or misfiring fault occurs after this, the data of the fault which occurred first are overwritten.

The following PIDs are supported:

$00 Supported PIDs
The PIDs supported in this mode are output in a 4-byte word.

NOTE: The Data A and B bytes indicate that PIDs 02, 03, 04, 05, 06, 07, 08, 09, 0B, OC and OD are supported.

$02 Diagnostic trouble code
The diagnostic trouble code which caused the storage of freeze frame data is displayed.

$03 Status of injection system

Data
A: 0000 0010
B: 0000 0010

Data A - Status for bank 1
Data B - Status for bank 2

Bit 0 Open-loop control; the conditions for oxygen sensing are not yet fulfilled.
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 due to fault in 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
Output of calculated load as a percentage of the maximum load.
Display between 0% and 100%.
In the case of decimal output, conversion factor = 0.3921568
The decimal value displayed multiplied by 0.3921568 gives the load as a percentage.

$05 Engine coolant temperature
Output of the engine coolant temperature.
Display between -40 degree C and 215 degree C.
In the case of decimal output, conversion factor = 1

Offset = -40 degree C

Decimal value displayed multiplied by 1 minus 40 degree C gives the coolant temperature.

$06 HO2S integrator, bank 1
Output of the control value FR of the oxygen sensor closed-loop control, bank 1.

Display: Lean to -100%
Rich to 99.22%

In the case of decimal output, conversion factor = 0.78125

Offset = -100%

Decimal value displayed multiplied by 0.78125 minus 100% gives the HO2S integrator.

$07 HO2S adaptation, bank 1
Output of the adaptation value FRA of the oxygen sensor closed-loop control, bank 1.

Display: Lean to -100%
Rich to 99.22%

In the case of decimal output, conversion factor = 0.78125

Offset = -100%

Decimal value displayed multiplied by 0.78125 minus 100% gives the HO2S adaptation value.

$08 HO2S integrator, bank 2
Output of the control value FR of the oxygen sensor closed-loop control, bank 2.

Display: Lean to -100%
Rich to 99.22%

In the case of decimal output, conversion factor = 0.78125

Offset = -100%

Decimal value displayed multiplied by 0.78125 minus 100% gives the HO2S integrator.

$09 HO2S adaptation, bank 2
Output of the adaptation value FRA of the oxygen sensor closed-loop control, bank 2.

Display: Lean to -100%
Rich to 99.22%

In the case of decimal output, conversion factor = 0.78125

Offset = -100%

Decimal value displayed multiplied by 0.78125 minus 100% gives the HO2S adaptation value.

$OB Intake manifold pressure (absolute)
Output of the intake manifold pressure.

Display: 0 kPa to 255 kPa

In the case of decimal output, conversion factor = 1

$OC Engine speed
Output of the engine speed.
Display in rpm
In the case of decimal output, conversion factor = 0.25
Decimal value displayed multiplied by 0.25 gives the engine speed.

$OD Vehicle speed
Output of the speed.
In the case of decimal output, conversion factor = 1

Mode 3
Output of stored faults.
The Diagnostic Trouble Codes of all shedded, officially relevant* faults are displayed in Mode 3.

* Faults which switch on the Check Engine warning light

Mode 4
In Mode 4, the fault memory can be erased.

NOTE:
- The fault memories of all systems relevant to OBD are erased.
- If the fault memory is erased, Mode 5 and Mode 6 values are also reset. Furthermore, the adaptation values are neutralized.

Mode 5
Output of oxygen sensor data.
The values of the last oxygen sensor test carried out (test identification TID) can be read out for every oxygen sensor with its nominal values.

$01 Rich-lean threshold voltage
Programmed fixed value: e.g. 0.430 V.
In the case of decimal output, conversion factor = 0.005
Decimal value displayed multiplied by 0.005 gives the threshold voltage.

$02 Lean-rich threshold voltage
Programmed fixed value: e.g. 0.430 V.
In the case of decimal output, conversion factor = 0.005
Decimal value displayed multiplied by 0.005 gives the threshold voltage.

$07 Minimum voltage of oxygen sensor during the test

Minimum: e.g. 0.000 V
Maximum: e.g. 0.385 V
Test value: e.g. 0.180 V

In the case of decimal output, conversion factor = 0.005
Decimal value displayed multiplied by 0.005 gives the voltage voltage of oxygen sensor.

$08 Maximum voltage of oxygen sensor during the test

Minimum: e.g. 0.480 V
Maximum: e.g. 0.960 V
Test value: e.g. 0.855 V

In the case of decimal output, conversion factor = 0.005
Decimal value displayed multiplied by 0.005 gives the the voltage voltage of oxygen sensor.

$09 Time between two transtions

Minimum: e.g. 0.00 s
Maximum: e.g. 1.52 s
Test value: e.g. 0.40 s

In the case of decimal output, conversion factor = 0.04
Decimal value displayed multiplied by 0.04 gives the time.

$30 Shift in oxygen sensor characteristic towards rich

Minimum: e.g. 0.00 s
Maximum: e.g. 1.20 s
Test value: e.g. 0.12 s

In the case of decimal output, conversion factor = 0.04
Decimal value displayed multiplied by 0.04 gives the time.

$31 Shift in oxygen sensor characteristic towards lean

Minimum: e.g. 0.00 s
Maximum: e.g. 1.20 s
Test value: e.g. 0.00 s

In the case of decimal output, conversion factor = 0.04
Decimal value displayed multiplied by 0.04 gives the time.

$32 Averaged period

Minimum: e.g. 0.00 s
Maximum: e.g. 3.00 s
Test value: e.g. 0.40 s

In the case of decimal output, conversion factor = 0.04
Decimal value displayed multiplied by 0.04 gives the time.

Mode 6
The test results of components or systems which are not continuously monitored are output in mode 6. At the same time, limit values are provided. The test results are referred to as TIDs (Test Identification). The components or systems are distinguished by CIDs (Component Identification).

The following components or systems are supported:

TID $01 Catalytic converter monitoring
The catalytic converters (bank 1/bank 2) are monitored individually and for the sum of the emissions. There are two threshold values for individual monitoring:
- AHKATMN for the OK detection and
- AHKATMX for the defect detection.

For the sum of the emissions, there is the AHKATSB threshold value. A number (ahkat) which is between 0 and 1 is used as a measure for the aging of the catalytic converters.

0-good
1-poor

AHKATS - Sum total of ahkat + ahkat2
A - Symmetry line
HC - HC emissions

The cases for catalytic converter bank 1 are shown in the graphic. The same applies for bank 2.

1 TWC 1 OK
2 TWC 1 OK
3 TWC 1 OK
4 TWC 1 faulty (P0420)
5 TWCs 1 and 2 faulty (P0420 and P0430)
6 TWC 1 faulty (P0420)

In the case of the individual CIDs, the limit values (maximum) and the test value of the last test are output.

Maximum: fault, if the test value is greater than the limit value.

The following CIDs can be displayed:

$00 Test not yet carried out

$05 Conversion bank 1
The values displayed can be multiplied by the factor 0.0039 to find the ahkat or AHKATMX values.

$06 Conversion bank 2
The values displayed can be multiplied by the factor 0.0039 to find the ahkat or AHKATMX values.

NOTE: CID $05 and $06 are displayed if the test was completed without faults. The values provide information as to how far the catalytic converters still are from the limit values.

$07 Checksum error, bank 1 and bank 2
DTC P0420 and P0430 in memory.
The values displayed can be multiplied by the factor 0.0078 to find the ahkat and ahkat2 or AHKATS values.

$08 Checksum range error, bank 1
DTC P0420 in memory.
The values displayed can be multiplied by the factor 0.0039 to find the ahkat or AHKATMX values.

$09 Checksum range error, bank 2
DTC P0430 in memory.
The values displayed can be multiplied by the factor 0.0039 to find the ahkat or AHKATMX values.

$OA Conversion, bank 1
The values displayed can be multiplied by the factor 0.0039 to find the ahkat or AHKATMX values.

$OB Conversion, bank 2
The values displayed can be multiplied by the factor 0.0039 to find the ahkat or AHKATMX values.

NOTE: CID $OA and $OB are displayed if the function was carried out with the Porsche System Tester 2 in the Short test menu.

TED $03 Secondary air system
The following CIDs can be displayed:

$00 Test not yet carried out

$01 Secondary air system, bank 1
Relative secondary air mass

$04 Secondary air system, bank 2
Relative secondary air mass

NOTE:
- The relative secondary air mass is the measured secondary air mass relative to the expected nominal value (optimal value) in this operating point. The optimal value is detected with a faultless system. The nominal value is primarily dependent on exhaust back pressure, geographical altitude and voltage supply.
- A fault is present if the relative secondary air mass does not exceed the diagnosis threshold value.
- The values displayed can be multiplied by the factor 0.0078 to find the applied values.

TID $05 Fuel tank ventilation system
For the fuel tank ventilation system, several tests are carried out consecutively but only one test value is output. This means that the subsequent test overwrites the preceding test value.

When all tests have been carried out, $OD (micro-leak test) is displayed.

If a different CID is displayed, the test was interrupted - either because a fault was present or, for example, the EVAP canister was excessively loaded.

The following CIDs can be displayed:
- $00 Test not yet carried out
- $0A Canister purge valve (leaking)
- $0B Shut-off valve, EVAP canister (blocked)
- $OC Major leak (pressure increase)
- $OD Minor leak (leakage volumetric flow)
- $OE Micro leak
- $11 Shut-off valve, EVAP canister (pressure reduction)
- $12 Major leak (pressure sensor)
- $13 Major leak (pressure sensor)
- $14 Tank vent valve (constantly open)

TID $09 coolant thermostat
Output of engine temperature

Display between 48 degree C and 143.25 degree C

In the case of decimal output conversion factor = 1

Offset = -48 degree C

Decimal value displayed multiplied by 0.75 minus 48 degree C gives the coolant temperature.

Mode 7
The Diagnostic Trouble Codes of all non-shedded, officially relevant* faults are displayed in Mode 7. This mode has the same structure as Mode 3.

* Faults which switch on the Check Engine warning light

Mode 9
The following vehicle information is displayed in Mode 9:
- Vehicle Identification Number
- Programme status (Calibration Identification Number)
- Control unit checksum (Calibration Verification Number).