Engine Controls - IM Readiness Code Status
01 10 07April 30, 2010
2023361
Vehicle Information
Diesel Engine Not Ready for I-M (Inspection Maintenance) Testing due to Readiness Codes Not Being Fully Set
The following symptoms may have occurred:
Diagnostic Trouble Codes were recently erased from the vehicle's engine control module (ECM).
TDI diesel is not ready for I/M (Inspection Maintenance) testing due to readiness codes not being fully set.
Tip:
This does not indicate any technical problems with the vehicle, only that more driving may be necessary to set full OBD readiness.
Checking readiness status through Guided Fault Finding (GFF) may incorrectly display readiness codes are set.
State emission testing equipment may display conflicting readiness status compared to the VAS 5052, VAS 6150 (or equivalent) test tool.
Tester displays gasoline monitor descriptions.
Emissions testing stations with out-of-date software may indicate a false fail" on TDI diesel vehicles.
Technical Background
To set some of the readiness codes on TDI diesel vehicles requires special driving conditions. If DTCs have been recently erased from the vehicle's ECM, the vehicle may require additional driving, under different conditions, to fully set OBD readiness parameters.
GFF is displaying incorrect data to determine OBD readiness.
Emissions testing stations with out-of-date software may be interpreting the incorrect data to determine correct OBD readiness.
MVB 89 will store correct data concerning OBD readiness. Figure 1 illustrates how to manually read MVB 89.
Interpreting OBD Readiness (MVB 89)
Byte 1 describes whether DTCs are stored and how many
Byte 1 Bits 0-6: Indicates how many DTC's in total are stored using binary code. In this case, 000 0000 = 0, no DTCs.
Byte 1 Bit 7: Indicates the condition of the MIL. In this, case 0 = OFF.
Byte 2 describes which functions are supported and the fuel type
Byte 2 Bit 0: Indicates support for continuous misfire monitor. In this case, 1 = supported.
Byte 2 Bit 1: Indicates support for continuous fuel system monitor. 1 = supported.
Byte 2 Bit 2: Indicates support for continuous comprehensive component monitoring. 1 = supported. Byte 2 Bit 3: Indicates support for spark ignition or compression ignition monitors. 1 = compression ignition (diesel).
Byte 2 Bit 4: Indicates misfire monitor readiness. 0 = complete.
Byte 2 Bit 5: Indicates fuel system monitor readiness. 0 = complete.
Byte 2 Bit 6: Indicates comprehensive component monitor readiness. 0 = complete.
Byte 2 Bit 7: Not used.
Byte 3 describes which monitors are supported on this vehicle
Byte 3 Bit 0: Indicates support for NMHC Catalyst Monitor. 1 = supported.
Byte 3 Bit 1: Indicates support for NOx/SCR Aftertreatment Monitor. 1 = supported.
Byte 3 Bit 2: Currently not used on diesel vehicles.
Byte 3 Bit 3: Indicates Boost Pressure System Monitor. 0 = NOT supported.
Byte 3 Bit 4: Currently not used on diesel vehicles.
Byte 3 Bit 5: Exhaust Gas Sensor Monitor. 0 = NOT supported.
Byte 3 Bit 6: Indicates Diesel Particle Filter Monitoring. 0 = NOT supported.
Byte 3 Bit 7: EGR/VVT System Monitor. 1 = supported.
Byte 4 provides the readiness status of the SUPPORTED systems from Byte 3
Byte 4 Bit 0: Indicates readiness of NMHC Catalyst Monitor. 0 = complete.
Byte 4 Bit 1: Indicates readiness of NOx/SCR Aftertreatment Monitor. 1 = NOT COMPLETE.
Byte 4 Bit 2: Currently not used on diesel vehicles.
Byte 4 Bit 3: Indicates Boost Pressure System Monitor readiness. 0 = complete.
Byte 4 Bit 4: Currently not used on diesel vehicles.
Byte 4 Bit 5: Exhaust Gas Sensor Monitor readiness. 0 = complete.
Byte 4 Bit 6: Indicates Diesel Particle Filter Monitoring readiness. 0 = complete.
Byte 4 Bit 7: EGR/VVT System Monitor readiness. 0 = complete.
Quick Reference Table
Future VAS 5052, 61 50/GFF software will be able to correctly display OBD system readiness status.
1. To check the correct status of OBD readiness, refer to MVB 89 and the supplemental information in the Technical Background section.
2. If any OBD system indicates incomplete monitoring ("1" shown in Byte 4) with no DTCs stored in the ECM, no repair is necessary.
3. The vehicle requires additional driving to complete the OBD readiness checks. Drive the vehicle until all applicable monitoring systems indicate complete readiness before attempting emissions testing.
Warranty
Information Only.
Required Parts and Tools
No Special Parts Required.
All part and service references provided in this Technical Bulletin are subject to change and/or removal.
Always check with your Parts Dept. and Repair Manuals for the latest information.