OBD (II): Introduction: General: Notes

This article is intended for trained automotive workshop personnel who have successfully completed Porsche training seminars on the respective systems and who possess the necessary theoretical and practical knowledge to perform work on complex systems.

The basic prerequisite for all work on the DME is the acknowledgment and observance of safety regulations and warnings; these are contained in "NOTES" through out this aticle.

NOTE: The following diagnosis and troubleshooting procedures are oriented toward and described for left-hand drive vehicles. Plugs and jacks specified may have different pin assignments for right-hand drive vehicles, which could lead to both misinterpretation during troubleshooting and to unpredictable accidents. Therefore, work should not be performed on right-hand drive vehicles without the correct circuit diagram or diagnosis and troubleshooting descriptions for right-hand drive vehicles.

This OBDII article DME 7.1.1 covers the following vehicles:

Cayenne with V8 turbo engine, as of model year 2003
Cayenne with V8 naturally-aspirated engine, as of model year 2003
Cayenne with V6 naturally-aspirated engine, as of model year 2004

This article describes the diagnosis and troubleshooting procedures for the engine control module DME 7.1.1. It is based on the OBD II versions (USA version, OBD = On-Board Diagnosis). This includes the EOBD (European OBD) and RoW (Rest of the World) versions that were adapted to the respective national laws or regulations regarding diagnosis.

The main differences between the OBD II and EOBD versions include the fuel tank leakage test required by law in the USA and the criteria for storing faults and activating the CHECK ENGINE light (abbreviated CE below), which is also referred to as the MIL (Malfunction Indicator Light).

The following functions are assured by the OBD II system:

Detection of combustion misfiring
Monitoring the Efficiency of the Catalytic Converter
Monitoring the fuel tank ventilation system
Monitoring the fuel tank system for leaks
Monitoring secondary air injection.
Monitoring the adaptation limits (e.g. of oxygen sensing, boost pressure control)
Monitoring the oxygen sensors
Monitoring the thermostat and water temperature sensor
Monitoring positive crankcase ventilation (via lambda adaption).
Monitoring the transmission (Tiptronic control module)
Monitoring emission-relevant sensors and actuators associated with the DME (previous scope of OBD 1)
Triggering the Check Engine light and storing faults in the memory
Indication of monitoring readiness (Ready codes, see "READY STATUS " section in chapter entitled "Definition of terms")
Output of existing diagnostic trouble codes (DTCs)
Storage of defined operating parameters in the event of a fault (including freeze frame)
Functional checks of the OBD system (warm-up cycle, driving cycle)
Communication with standardized control-module tester (scan tool) in the prescribed modes
Standardized read-out of operating data such as rpm, temperature, etc.