HW33 DTC P1445: CHECK PURGE FLOW (PF) SENSOR HIGH VOLTAGE TO PCM

Continuous Memory Diagnostic Trouble Code (DTC) P1445 indicates that Self-Test has detected a PF sensor circuit input above the maximum.

Possible Causes:

  • PF shorted to VPWR (Vehicle Power Supply).
  • PF open circuit.
  • PWR GND open circuit.
  • Damaged purge flow (PF) sensor.
  • Damaged PCM.

Disconnect PF sensor.

Check for loose pins or broken wires by pulling moderately on the PF and PWR GND circuits at PF sensor harness connector.

Repair as necessary.

Reconnect PF sensor.

Connect scan tool.

Key on, engine off.

Note: PF sensor input to the PCM range is 0.40 to 4.80 volts.

Access EVAPPF PID.

Key off.

Was EVAPPF PID voltage greater than 4.80 volts?

Yes = GO to HW34.

No = Fault is an intermittent DTC P1445. GO to HW39.

HW34 CHECK VPWR RESISTANCE FOR SHORT TO PF CIRCUIT IN PF SENSOR

Key off.

Disconnect PF sensor.

Allow the vehicle and PF sensor to cool down or warm up to a room temperature 13°C to 27°C (55° F to 80°F) before taking a resistance measurement on the PF sensor. This can take 15 to 20 minutes.

Measure resistance between VPWR and PF pins on the PF sensor.

Is resistance between 40 and 230 ohms?

Yes = GO to HW35

No = REPLACE damaged PF sensor. RESTORE vehicle. GO to HW42.

HW35 CHECK PF SENSOR VOLTAGE INPUT TO PCM

Key on, engine off.

Measure PF circuit voltage at PF sensor harness connector to battery negative post.

Key off.

Was voltage greater than 10.5 volts?

Yes = GO to HW36.

No = GO to HW37.

HW36 CHECK PF CIRCUIT FOR SHORT TO VPWR IN HARNESS

Install breakout box, leave PCM disconnected.

Key on, engine off.

Measure resistance between PCM test pin 11 and PCM test pins 24 or 103.

Is the voltage greater than 10.5 volts?

Yes = REPAIR short circuit. RESTORE vehicle. COMPLETE PCM Reset to clear DTCs. RERUN Quick Test.

No = REPLACE damaged PCM. RESTORE vehicle. RERUN Quick Test.

HW37 CHECK PF CIRCUIT FOR OPEN IN HARNESS

Install breakout box, leave PCM disconnected.

Measure resistance of PF circuit between PCM test pin 11 and PF sensor harness connector.

Is the resistance less than 5.0 ohms?

Yes = GO to HW38.

No = REPAIR open circuit. RESTORE vehicle. COMPLETE PCM Reset to clear DTCs. RERUN Quick Test.

HW38 CHECK PWR GND CIRCUIT FOR OPEN IN HARNESS

Measure resistance of PWR GND circuit between PCM test pin 24 or 103 and PF sensor harness connector.

Is the resistance less than 5.0 ohms?

Yes = REPLACE damaged PCM. RESTORE vehicle. RERUN Quick Test .

No = REPAIR open circuit. RESTORE vehicle. COMPLETE PCM Reset to clear DTCs. RERUN Quick Test.

HW39 CHECK PURGE FLOW SENSOR CIRCUIT FOR INTERMITTENT PF OPEN OR VPWR SHORT

Key on, engine off.

Access EVAPPF PID.

Observe EVAPPF PID for an indication of a fault while performing the following:

  • Lightly tap on PF sensor; wiggle PF sensor connector and harness between sensor and PCM. A fault is indicated by a sudden change in EVAPPF PID voltage (greater than 4.80 volts).

Is a fault indicated?

Yes = ISOLATE fault and REPAIR as necessary. RESTORE vehicle. COMPLETE PCM Reset to clear DTCs. RERUN Quick Test.

No = UNABLE to duplicate or identify fault at this time. GO to Pinpoint Test Step Z1 with the following data:

PF PID and a list of Possible causes.

HW40 DTC P0443: INSPECT EVAP CANISTER PURGE VALVE CIRCUIT FOR INTERMITTENT FAILURE

Continuous Memory Diagnostic Trouble Code (DTC) P0443 may indicate an EVAP canister purge valve circuit failure.

Possible causes:

  • Damaged EVAP canister purge valve.
  • EVAP CANISTER PURGE or VPWR circuit open.

Rerun KOEO, KOER Self-Tests and retrieve Continuous Memory DTCs.

Is DTC P0443 present in Continuous Memory Self-Test only?

Yes = GO to HW41.

No = GO to HW1.

HW41 CHECK EVAP CANISTER PURGE VALVE CIRCUIT INTERMITTENT OPEN OR SHORT

Install breakout box, leave PCM disconnected.

Measure resistance between PCM test pin 67 or PCM test pin 56 and PCM test pin 71, while performing the following:

  • Lightly tap on the EVAP canister purge valve and observe a resistance change.
  • Wiggle the EVAP canister purge valve connector and vehicle harness between the valve and the PCM, observe a resistance change.

Does the resistance reading change to below 30 ohms or above 90 ohms (vehicles with test pin 67) or above 38 ohms (vehicles with test pin 56)?

Yes = ISOLATE fault and REPAIR as necessary. RESTORE vehicle. COMPLETE PCM Reset to clear DTCs. RERUN Quick Test.

No =  UNABLE to duplicate or identify fault at this time. GO to Pinpoint Test Step Z1 with the resistance readings and list of Possible causes.

HW42 VERIFICATION OF EVAPORATIVE EMISSION SYSTEM REPAIR USING ROTUNDA EVAPORATIVE EMISSION SYSTEM LEAK TESTER

Plug or tape atmospheric vent cap on EVAP canister (if applicable).

Remove fuel filler cap at fuel filler pipe.

Install Rotunda Evaporative Emission System Leak Tester 134-00056 or equivalent including the nitrogen or argon gas supply and pressure regulator.

Disconnect and plug fuel vapor hose to PF sensor (or EVAP canister purge valve on Ranger) from intake manifold at the intake manifold vacuum source.

Pressurize the EVAP system at 6.74 kPa (27 in-H 2 O) with tester.

Observe tester installation leak self-test for two minutes and then the EVAP system leak test.

Listen for a vacuum leak noise and check for substantial fuel vapor odors at isolated areas in the EVAP system.

Does the pressure applied to the EVAP system hold?

Yes = REMOVE plug and RECONNECT fuel vapor hose from PF sensor (or EVAP canister purge valve) at intake manifold vacuum source. REMOVE EVAP System Leak Tester. REINSTALL fuel filler cap. TIGHTEN cap only one eighth turn so that cap initially clicks by sound or touch. COMPLETE PCM Reset to clear DTCs.

No =  Access EVAPPDC PID on scan tool. DRIVE vehicle (including a steady accelerator speed over 80 km/h (50 mph) until EVAPPDC PID shows 75 percent duty cycle). Then maintain approximate speed until duty cycle reaches zero percent. After additional two minute drive, bring vehicle to an idle. RERUN Quick Test . VERIFY a symptom no longer exists. GO to HW43.

HW43 CHECK LOCATION OF EVAPORATIVE EMISSION SYSTEM PRESSURE LEAK

Systematically isolate area of potential pressure leak.

Close off pressure to EVAP system.

Disconnect and plug fuel vapor hose from fuel tank at EVAP canister.

Apply controlled pressure at 6.74 kPa (27 in-H 2 O to the EVAP system with the leak tester.

If pressure now holds, GO to the Powertrain/Engine Group, Evaporative Emissions Section in the Workshop Manual for EVAP canister diagnosis.

If system pressure cannot hold, close pressure supply to system.

Disconnect and plug fuel vapor hose from EVAP canister at EVAP canister purge valve.

Again, apply controlled pressure to the EVAP system.

Does the pressure hold?

Yes = REMOVE plugs. RECONNECT fuel vapor hose at EVAP canister. RETURN to Pinpoint Test Step HW14 to check EVAP canister purge valve integrity on Ranger or Pinpoint Test Step HW18 to check EVAP canister purge valve integrity on Mustang. REMOVE EVAP System Leak Tester. REINSTALL fuel filler cap. COMPLETE PCM Reset to clear DTCs. Access EVAPPDC PID on scan tool. DRIVE vehicle (including a steady accelerator speed over 80 km/h (50 mph) until EVAPPDC PID shows 75 percent duty cycle). Then maintain approximate speed until duty cycle reaches zero percent. After additional two minute drive, bring vehicle to an idle. RERUN Quick Test. VERIFY a symptom no longer exists. REMOVE plugs.

No = CHECK for fuel vapor hose cracks or fuel vapor valve damage. EXAMINE and SECURE fuel vapor hose connections to components. REPAIR or REPLACE as necessary. REMOVE EVAP System Leak Tester. REINSTALL fuel filler cap. COMPLETE PCM Reset to clear DTCs. Access EVAPPDC PID on scan tool. DRIVE vehicle (including a steady accelerator speed over 80 km/h (50 mph) until EVAPPDC PID shows 75 percent duty cycle). Then maintain approximate speed until duty cycle reaches zero percent. After additional two minute drive, bring vehicle to an idle. RERUN Quick Test . VERIFY a symptom no longer exists.