Examination
2. Remove the sensor and inspect it. Check for dirt on the inlet screen, especially if the vehicle is equipped with an OBD-I diagnostic system and if the system has detected a fault code 158. If the screen is clogged, clean it. On 1993 to 1997 V-engines, push the throttle valve from the intake side and make sure it moves back and forth smoothly without binding. Install the sensor in place and ensure that its seating surfaces are well sealed and do not allow air to pass through.
3. Connect the voltmeter with thin probes from the outside of the connector to the B+ and GRD contacts (figure 5.3, a, b). Turn on the ignition. The voltmeter should show the battery voltage. If there is no voltage, disconnect the connector and check the integrity of the ground connection to the GRD contact.
- a) No voltage and no ground connection: Check the ground circuit.
- b) No voltage, mass connected: check the power supply target.
Repair the chain if necessary.
All 4-cylinder and V-shaped engines produced since 1998
4. Measure the voltage from the outside of the connector at the MAF contact - first with the engine off, then with the engine idling (see figure 5.3.6).
5. If the sensor has a 3-pin connector, the voltage when the engine is not running should be within 1.0-15 V, and when idling - 1.5-5.0 V.
6. If the sensor has a 4-pin connector, the voltage when the engine is not running should be around zero, and when idling - 0.6-0.7 V (on engines produced since 1998 (0.6-1.1 V).
7. Increase engine speed and apply pressure. how the voltage changes. It should gradually increase to approximately 2.0 V. Voltage surges indicate that the sensor is faulty.
V-shaped engines produced from 1993 to 1997
8. Disconnect the air duct from the sensor (to do this, push the flap inside the sensor). Turn on the ignition, but do not start the engine.
9. Measure the voltage at the MAE contact on the outside of the connector (connect the second probe of the voltmeter to the GND contact) (see Figure 5.3,a). When the valve is closed, the voltage should be 4.0 V. As the valve moves inward, the voltage should decrease as follows:
- a) Open 1/4 - 2.4 V
- b) Open 1/2-1.6 S
- c) Open 3/4-0 Q 8
- d) Fully open - 0.4 V
All models
10. Reinstall the air duct (if it was removed).
Note: If you experience drivability issues and the above tests do not reveal any fault, have the sensor checked by a specialist. Not all sensor faults can be detected with a voltmeter. The ECU detects this type of malfunction and the diagnostic system can store a corresponding code.
Replacement
11. Disconnect the negative cable from the battery.
Caution: If your vehicle's audio system is equipped with a theft-deterrent feature, make sure you have the unlock code before disconnecting the battery.
12. Disconnect the electrical connector from the air flow sensor.
13. Loosen the nuts or bolts and remove the sensor (figure 5.13).
14. Installation is carried out in reverse order.