On Board Diagnostic (OBD), Function

On Board Diagnostic (OBD), Function

The instrument cluster is controlled by an internal microprocessor with On Board Diagnostic (OBD) capability. If malfunctions occur in monitored sensors and components, Diagnostic Trouble Codes (DTC) will be stored in memory.

If OBD recognizes instrument cluster malfunctions related to the:
- odometer
- distance impulse number (K number)
- speedometer calibration

the trip odometer display will change to show "dEF.".

In this case, replace speedometer.

Other malfunctions recognized by OBD will not cause the trip odometer display to change as described above.

However, before performing any troubleshooting or inspection, always begin by checking for DTCs using the On Board Diagnostic (OBD) program. DTCs stored in memory are retrieved/checked with either VAG 1551/1552 Scan Tools.