Oxygen Sensor and Oxygen Regulation, Checking

Checking Oxygen Sensor And Oxygen Regulation

Engine code MV

Note: There must be no leaks in the exhaust system between the cylinder heads and the catalytic converter.

Requirement

- Engine oil temperature min. 80°C (176°F)





- Connect CO test equipment hose to the sampling point on left exhaust pipe using Sun 120.239 adapter (arrow)

Test step I

- Let engine run approximately 2 minutes at idle and read CO-content





- Oxygen sensor connected
- Remove hose (1) from pressure regulator (2) and plug hose
CO should increase briefly. then drop in value to 0.3 - 1.1%

If NO:
Proceed to determine whether the problem is with the oxygen sensor or with the control unit

Test step II

- Shut off engine





- Disconnect RPM signal wire

Note: As of 9-87 production this connection has moved to the right side of the engine compartment (in front of the air flow sensor).

- Disconnect oxygen sensor

Note: The oxygen sensor must be disconnected with the ignition OFF to cancel the memory in the control unit.

- Start engine
- Hold disconnected (green) oxygen sensor wire from the control unit to ground
CO content must increase

If NO
- Check wire connection on control unit, refer to Fuel Delivery and Air Induction - Testing and Inspection - Procedures - Electrical Testing - Ignition and Injection System Testing and Inspection, test step II

If OK
- Replace control unit and recheck

Note: If test step I is not OK but test step II is OK, the oxygen sensor is defective.