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Home › Acura › 1997 › 2.5TL › Repair and Diagnosis › Engine Performance › System › Engine Controls - Tests W/Codes › Circuit Tests › DTC P0139: Rear Ho2S-2 Slow Response

DTC P0139: Rear Ho2S-2 Slow Response

  1. Perform PCM reset procedure. See PCM RESET PROCEDURE/CLEARING CODES  . Start engine and run at 3000 RPM with no loads and transmission in Park or Neutral, until radiator fan comes on. Quickly increase engine to 5000 RPM and release throttle. Using scan tool, check HO2S-2 output data. If voltage does not stay within 0.45-0.55 volt for one minute, go to next step. If output stays within 0.45-0.55 volt for one minute, replace HO2S-2.
  2. Turn ignition off. Disconnect HO2S-2 4-pin connector. Start engine and run at 3000 RPM with no loads and transmission in Park or Neutral, until radiator fan comes on. Allow engine to idle. Measure voltage between HO2S-2 terminals No. 1 (Blue wire) and No. 2 (White wire). See Figure . If voltage is more than 0.1 volt, go to next step. If voltage is 0.1 volt or less, replace HO2S-2.
  3. Turn ignition off. Reconnect HO2S-2 4-pin connector. Start engine. Measure voltage between PCM 22-pin connector terminals No. 14 (Blue/Red wire) and No. 22 (Green/Blue wire). If voltage is 0.1 volt or less, repair open or short in Blue/Red wire between PCM and HO2S-2. If voltage is more than 0.1 volt, substitute a known good PCM, then recheck. If symptom or indication goes away, replace original PCM.
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