LEMON Manuals: Even more car manuals for everyone: 1960-2025
Home >> Acura >> 1996 >> 3.5RL >> Repair and Diagnosis >> Engine Performance >> System >> Engine Controls - Tests W/Codes >> Circuit Tests >> DTC P1459 - EVAP Purge Flow Switch Fault
April 5, 2026: LEMON Manuals is launched! Read the announcement.

DTC P1459 - EVAP Purge Flow Switch Fault

  1. Connect and operate scan tester, following manufacturer's instructions. Clear codes. Test-drive vehicle while engine coolant temperature is lower than 158°F (70°C), A/T in D4 position, and engine speed at 2200-2700 RPM. Retrieve codes. If DTC P1459 appears, go to next step. If DTC P1459 does not appear, problem is intermittent. Inspect for poor connections or loose wires associated with EVAP purge flow switch and PCM, then repair as necessary.
  2. Turn ignition off. Inspect EVAP system vacuum lines for misrouting, leaks, clogging, or breaks. If vacuum lines are okay, go to next step. Repair or replace vacuum lines as necessary.
  3. Disconnect vacuum hose from EVAP purge flow switch. Connect vacuum hose to hose. With engine temperature lower than 158°F (70°C), start and run engine at 2000-2700 RPM. If vacuum is less than 2.4 in. Hg, go to next step. If vacuum is 2.4 in. Hg or greater, go to step 8).
  4. Turn ignition off. Reconnect vacuum hose which was disconnected in previous step. Disconnect upper vacuum hose from EVAP canister diaphragm. Connect vacuum gauge to hose. With coolant temperature lower than 158°F (70°C), start engine. If vacuum exists, go to next step. If vacuum does not exist, temporarily substitute known good EVAP control canister, then retest system.
  5. Turn ignition off. Reconnect vacuum hose which was disconnected in previous step. With coolant temperature less than 158°F (70°C), start engine. Measure voltage between terminals No. 12 and 18 at PCM connector "A". See Figure . If voltage is 0.1 volt or less, go to next step. If voltage is greater than 0.1 volt, temporarily substitute known good PCM, then retest system.
  6. Turn ignition off. Unplug 2-pin connector from EVAP purge control solenoid valve. Turn ignition on. Measure voltage at Black/Yellow wire at harness connector. If battery voltage exists, go to next step. If battery voltage does not exist, repair open Black/Yellow wire between EVAP purge control solenoid valve and fuse panel.
  7. With coolant temperature less than 158°F (70°C), start engine. Measure voltage between Black/Yellow and Red wires at harness connector. If battery voltage exists, replace EVAP purge control solenoid valve. If battery voltage does not exist, repair open Red wire between EVAP purge control solenoid valve and PCM.
  8. Turn ignition off. Unplug 2-pin connector from EVAP purge flow switch. Turn ignition on. Test for battery voltage between Brown and Black wires at harness connector. If battery voltage does not exist, go to next step. If battery voltage does not exist, temporarily substitute known good EVAP purge flow switch, then retest system.
  9. Measure voltage between PCM terminals A12 and B11. If battery voltage exists, repair open in Brown wire between EVAP purge flow switch and PCM 16-pin connector. If battery voltage does not exist, temporarily substitute known good PCM, then retest.
scientia non olet · About LEMON Manuals