Inspection and Verification
1. Verify the customer concern is with the evaporative emission (EVAP) system.
2. Visually inspect for the following obvious signs of mechanical damage.
Visual Inspection Chart
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3. If the concern remains after the inspection, connect the scan tool to the data link connector (DLC) located beneath the instrument panel and select the vehicle to be tested from the scan tool menu. If the scan tool does not communicate with the vehicle:
- check that the program card is correctly installed.
- check the connections to the vehicle.
- check the ignition switch position.
4. If the scan tool still does not communicate with the vehicle, refer to the scan tool manual.
5. Carry out the DATA LINK DIAGNOSTICS test. If the scan tool responds with:
- CKT914, CKT915 or CKT70 = ALL ECUS NO RESP/NOT EQUIP, refer to Section.
- NO RESP/NOT EQUIP for PCM, refer to the Powertrain Control/Emissions Diagnosis (PC/ED) manual.
- SYSTEM PASSED, retrieve and record the continuous diagnostic trouble codes (DTCs), erase the continuous DTCs and carry out the PCM KOEO self-test.
6. If the DTCs retrieved are related to the concern, go to the PCM Diagnostic Trouble Code (DTC) Index to continue diagnostics.
7. If the concern remains after the inspection, determine the symptom. GO to Symptom Chart .
PCM Diagnostics Trouble Code (DTC) Index
| DTC | Description | Source | Action |
| P0442 | Small leak detected in EVAP system (As small as 1.02 mm [0.040 inch]) | PCM | Go To Pinpoint Test A . |
| P0455 | Major leak or no flow detected | PCM | Go To Pinpoint Test B . |
| P0457 | Check for missing or leaking fuel filter cap | PCM | Go To Pinpoint Test A . |
| P1443 | Very small or no purge flow detected | PCM | Go To Pinpoint Test B . |
| P1450 | Excessive vacuum detected in the fuel tank | PCM | Go To Pinpoint Test C . |
| - | Any other PCM DTC | PCM | REFER to the Powertrain Control/Emissions Diagnosis (PC/ED) manual. |
Symptom Chart
| Condition | Possible Sources | Action |
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Test yourself
A quick Ford Mustang quiz: every answer comes with an explanation and a link to the manual page.