Definition of Terms

Definition of Terms

Warm-up cycle
The warm-up cycle is the time which the engine requires to reach operating temperature. To fulfil the warmup cycle condition, the engine temperature on start-up must not be higher than a specified value (e.g. 30 °C). The engine operating phase has to be long enough to reach a specified temperature (e.g. 70 °C). The warmup cycle condition is needed to count down or reduce the erase counter in the case of faults which have been recognized as corrected.

Driving cycle
A driving cycle consists of starting the engine, running the engine or driving until oxygen sensing becomes active, and then stopping the engine. Since the system cannot know when the engine will be stopped, the diagnostic routines are started as soon as oxygen sensing is activated.

Trip
A trip is a driving cycle after a rest period that enabled the diagnostic system to monitor all components and systems at least once. In the event of a fault, it may not be possible to perform all diagnostic routines under certain circumstances. For this reason, a replacement trip is recognized after an operating period of 1150 seconds. In other words, a driving cycle is recognized as a trip after this time, even if not all diagnostic routines were performed.

Ready status
The ready status menu item indicates whether the OBD system has performed the desired fault checks. It is not important whether or not a fault was found.

The ready status is displayed for the following sub-systems:

- TWC conversion
- Fuel tank ventilation system
- Secondary air system
- Oxygen sensor
- Oxygen sensor heating

The ready status for a sub-system is reset to zero if a fault was present for the sub-system in question and the fault is erased.

Freeze
frame Freeze frame data are the momentary operating conditions that are recorded in the memory when a fault occurs.
The following operating conditions can be stored with each fault:

- Fault DTC
- Oxygen sensing status, bank 1
- Oxygen sensing status, bank 2
- Load value
- Engine temperature
- Oxygen sensing value FR, bank 1
- Adaptation value FRA, bank 1
- Oxygen sensing value FR2, bank 2
- Adaptation value FRA 2, bank 2
- Engine speed
- Vehicle speed

Fault shedding
When a fault is recognized during a diagnostic routine, it is stored as a suspected fault. At the same time, a fault shedding counter is started that contains a certain value. During additional diagnostic routines, the shedding counter will be decreased by 1 if the fault is recognized in the same area window. If the shedding counter has reached the value 0, the fault is considered as shedded.

Fault healing
When a fault is recognized during a diagnostic routine, it is stored as a suspected fault. At the same time a fault healing counter is started that contains a certain value. During additional diagnostic routines, the fault healing counter will be decreased by 1 if the fault is not recognized in the same area window. If the fault healing counter has reached the value 0, the fault is considered to be healed. If the fault has triggered the Malfunction Indicator Light (MIL) then the latter is switched off as long as it is not triggered by any further faults.

Fault erasing counter
For each recognized fault, an individual fault erasing counter is kept. The counter determines the memory storage time of the respective fault. The first time the fault is recognized, the fault erasing counter is set to 80. If an unshedded fault is recognized as healed, the fault erasing counter is set to 10. Each time a shedded fault is recognized, the fault erasing counter is set 40. It retains this value until fault healing is recognized. After each warm-up operating cycle the fault erasing counter is decreased by 1, when the fault in question is recognized as unshedded or healed. When the fault erasing counter reaches the value 0, the fault is erased from the memory.

Diagnosis software numbers classification

M 15 XX
911 Carrera 4 as of model '99 USA

M 16 XX
911 Carrera 4 as of model '99 RoW
911 Carrera 2 as of model '00 RoW
Exhaust standard EU 2

M 17 XX
Boxster S as of model '00 USA

M 18 XX
Boxster S as of model '00 RoW
Exhaust standard EU 2

M 19 XX
Boxster as of model '00 USA

M 20 XX
Boxster as of model '00 RoW
Exhaust standard EU 2

M 24 XX
911 Carrera 2/4 as of model '00 USA

M 25 XX
Boxster as of model '00 RoW
Exhaust standard EU 3

M 26 XX
Boxster S as of model '00
Exhaust standard EU 3

M 27 XX
911 Carrera 2/4 as of model '00
Exhaust standard EU 3

M 28 XX
Boxster as of model '00
Exhaust standard D4

M 29 XX
911 Carrera 2/4 as of model '00
Exhaust standard D4

M 30 XX
Boxster S as of model '00 Exhaust standard D4

Important Notes

Adaptation
The DME control module must perform a learning and adaptation routine if
- The battery was disconnected
- The DME control module connector was unplugged
- A new DME control module has been installed
- The throttle part has been replaced.

To initiate adaptation:
1. Switch on the ignition for 1 minute without starting the engine.
Do not press the accelerator.

2. Switch off the ignition for at least 10 seconds.

The following conditions must be fulfilled, otherwise learning is not possible:
- Stationary vehicle
- Accelerator pedal angle less then 0.8 %
- Battery voltage > 10 V
- Engine temperature between 5 °C and 100 °C
- Intake air temperature > 10 °C

Special tool 9637
The fault memory must be read out and saved before special tool 9637 is connected, as the fault memory is erased when the control module connector is unplugged.