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Code 23 - Mass Airflow Sensor

NOTE: Refer to illustration for ECU connector and terminal identification. See Figure -Figure .
  1. Ensure ECU is connected. Turn ignition on. Measure voltage between ECU connector E30, terminal No. 5 (backprobe) and ground. Voltage should be 0-.3 volt. Measure voltage between ECU connector E31, terminal No. 1 and ground. No voltage should be present.
  2. Start and idle engine. About .8-1.2 volts should now be present between ECU connector E30, terminal No. 5 and ground. Zero voltage should be present between ECU connector E31, terminal No. 1 and ground. If voltages are to specification, repair ECU harness connector or replace ECU. If voltages are not to specification, go to next step.
  3. Turn ignition off. Disconnect MAF sensor connector. Turn ignition on. Measure voltage between MAF sensor connector terminal No. 1 (Yellow/Green wire) and ground. If voltage is 10-13 volts, go to next step. If voltage is not 10-13 volts, repair or replace MAF harness or connector.
  4. Turn ignition off. Disconnect ECU connector. Measure resistance between ECU connector E30, terminal No. 5 and MAF connector terminal No. 2 (Black/Blue wire), between ECU connector E30, terminal No. 22 and MAF connector terminal No. 3 (Black/Red wire), and between MAF connector terminal No. 3 (Black/Red wire) and ground. A maximum of 10 ohms should be present in all cases. If more than 10 ohms is present in any case, repair harness as necessary.
  5. Measure resistance between ECU connector E30, terminal No. 5 and ground, and between ECU connector E31, terminal No. 1 and ground. A minimum of one megohm should be present in both cases. If resistances are to specification, replace MAF sensor. If resistances are not to specification, repair or replace harness.
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