Code 70 (Oxygen Sensor)

OXYGEN SENSOR
Explanation
This trouble code is stored when a short or a break occurs at the oxygen sensor or on its supply wires. The prerequisite for this is an engine temperature of >158°F (>70°C) over a period of 3 minutes and load signal of 3.5 ms for 20 seconds..

NOTE: The system uses a substitute value of 0.45V until the defect is corrected.

Troubleshooting
- Check the oxygen sensor signal at operating temperature with status monitoring. The voltage value should fluctuate between 0.02 and 0.85 V.
- If sensor voltage not OK.: Detach connector for oxygen sensor, switch on ignition and measure voltage at connector (control unit side) (nominal value = 0.45 V). As displayed on screen.
- Check wire and oxygen sensor.
- If the oxygen sensors have been interchanged (DME control unit I operates with sensor II and vice versa), this defect code will be stored in both control units. The mixture is too rich in one group of cylinders and too lean in the other.
- Proceed with displayed scan tool diagnostic instructions where applicable.