General Information

Engines

2.5L (2497cc) KL-DE 60-degree naturally aspirated V6 (Japanese models use KL-ZE variant)

• Mazda Millenia
• Eunos 800
• Xedos 9

2.3L (2255cc) KJ-ZEM 60-degree Lysholm supercharged Miller Cycle V6

• Mazda Millenia S
• Eunos 800M
• Xedos 9 Miller

Catalyst Configurations

• Three o² sensor system (KL engine with one catalytic converter)
  • A front sensor is positioned on the LH bank and a middle sensor is positioned on the RH bank upstream of the catalyst for closed loop fuel control.  A rear sensor is mounted downstream of the catalyst to monitor its efficiency.
• Four o² sensor system (KJ / KL engine with three catalytic converters)
  • Front sensors are mounted upstream of the RH and LH warm-up three-way catalysts (WU-TWC) for closed loop fuel control.  Rear sensors are mounted downstream of the WU-TWCs to monitor their efficiency.

DRIVE MODE Conditions

DRIVE MODE 1 - ECU adaptive memory initialization

DRIVE MODE 2 - EGR system repair verification

DRIVE MODE 3 - Oxygen sensor and catalyst repair verification

DRIVE MODE 4 - Evaporative emissions system repair verification

DRIVE MODE & SYSTEM READINESS

The engine management computer uses feedback from multiple sensors in order to tune fuel delivery and emissions-related equipment.

When performing a DRIVE MODE condition, the OBD system is inspected for proper operation.  All DRIVE MODE conditions must be performed to ensure that no DTCs are present and confirm SYSTEM READINESS.

The following systems are inspected during DRIVE MODE conditions.

• Exhaust gas recirculation (EGR) system operation
• Oxygen sensor operation
• Oxygen sensor heater circuit operation
• Catalytic converter operation
• Fuel system operation
• Misfire condition
• Evaporative emissions system operation

If the OBD system inspection could not be completed during a DRIVE MODE condition, the following causes are considered.

• The OBD system detected a malfunction
• The DRIVE MODE condition was not completed correctly

Disconnecting the battery will reset ECU memory.  Do not disconnect the battery during or after completing a DRIVE MODE condition.

An OBD interface can be used during each DRIVE MODE condition to monitor its completion status.  A completed status is indicated by a SYSTEM READINESS confirmation.

OBD-II Compliance & 1995 Models

Early implementations (before 1996) of OBD-II utilize a non-standard method of determining SYSTEM READINESS with DTC P1000 to indicate one or more DRIVE MODE conditions have not been completed.  Such vehicles are considered "OBD-I compliant" for emissions testing but are essentially OBD-II for troubleshooting purposes.

OBD Diagnostics

INFORMATION - When a vehicle malfunction is detected, first check for an illuminated Check Engine indicator and diagnostic trouble codes (DTCs).  If a DTC exists, diagnose using applicable DTC Inspection.  If a DTC does not exist and the Check Engine indicator does not illuminate or flash, diagnose using applicable Symptom Troubleshooting.

OBD PENDING TROUBLE CODES - Trouble codes appear when a problem is detected in a monitored system.  The Check Engine indicator is illuminated when a problem is detected in two consecutive drive cycles.  The code for a failed system is stored in ECU memory in the first drive cycle.  This code is called the pending code.  If the problem is not found in the second drive cycle, the ECU judges that the system returned to normal or the problem was mistakenly detected, and deletes the pending code.  If the problem is also found in the second drive cycle, the ECU determines that the system has failed, deletes the pending code, illuminates the check engine indicator, and stores the DTC.

OBD FREEZE FRAME DATA - This is the technical data which indicates indicates the engine condition at the time of the first malfunction.  This data will remain in ECU memory even if another emission-related DTC is stored, with the exception of the Misfire or Fuel System DTCs.  Once freeze frame data for the Misfire or Fuel System DTC is stored, it will overwrite any previous data and the freeze frame will not be overwritten again.

OBD ON-BOARD SYSTEM READINESS TEST - This shows OBD-II systems operating status.  If any monitor function is incomplete, an OBD-II interface will identify which monitor function has not been completed.  Misfires, Fuel System and Comprehensive Components (CCM) are continuous monitoring-type functions.  The catalyst, EGR system, evaporative emissions system, oxygen sensor circuit, and oxygen sensor heater circuit will be monitored under each drive cycle. The OBD-II diagnostic system is reinitialized by performing the DTC cancellation procedure or disconnecting the negative battery cable.

OBD DIAGNOSTIC MONITORING TEST RESULTS - These results are from the intermittent monitor system's technical data, which are used to determine whether the system is normal or not.  They also display the system's thresholds and diagnostic results.  The intermittent monitor system monitors the oxygen sensor, evaporative purge system, catalyst and EGR system.

OBD READ/CLEAR DIAGNOSTIC TEST RESULTS - This retrieves all stored DTCs in the ECU and clears the DTCs, Freeze Frame Data, On-Board Readiness Test Results, Diagnostic Monitoring Test Results and Pending Trouble Codes

OBD PARAMETER IDENTIFICATION (PID) ACCESS - The PID mode allows access to certain data values, analog and digital inputs and outputs, calculated values and system status information.  Since PID values for output devices are ECU internal data values, inspect each device to identify which output devices are malfunctioning.

[OBD-II Drive Modes - From 2002 Mazda Millenia factory service manual]