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DTC P1459: EVAP Purge Flow Switch Malfunction

  1. Start engine and hold at 3000 RPM with no loads and transmission in Park or Neutral, until cooling fan comes on. Perform PCM reset procedure. See PCM RESET PROCEDURE/CLEARING CODES . Connect SCS Service Connector (07PAZ-0010100) to 2-pin service check connector, located under passenger side of instrument panel. See Figure. Allow engine to idle. If DTC P1459 resets, go to next step. If DTC P1459, does not reset, problem is intermittent, system is okay at this time. Check for poor connections or loose wires at EVAP purge flow switch and PCM.
  2. Turn ignition off. Check EVAP system vacuum hoses for misrouting, breakage and clogging. If vacuum hoses are okay, go to next step. If vacuum hoses are not okay, repair or replace necessary.
  3. Disconnect EVAP purge flow switch 2-pin connector. Check for continuity between PCM 32-pin connector terminal No. 10 (Black wire) and PCM 16-pin connector terminal No. 20 (Brown wire). See Figure. If continuity exists, go to next step. If continuity does not exist, replace EVAP purge flow switch.
  4. Disconnect PCM 31-pin connector. Check for continuity between EVAP purge flow switch connector terminals No. 1 (Brown wire) and No. 2 (Black wire). If continuity exists, repair short to ground in Brown wire between EVAP purge flow switch and PCM. If continuity does not exist, substitute a known-good PCM and recheck. If DTCs do not reset, replace original PCM.
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