Vehicle applicability: This diagnostic supplement covers multiple Ford vehicles and engines. Follow the application named in the source below. Some references apply to vehicles other than Mustang.
Powertrain DTC Charts and Descriptions 4-109
Diagnostic Trouble Code (DTC) Charts and Descriptions
P144A - Evaporative Emission System Purge Vapor Line Restricted/Blocked (Continued)
All GO to Pinpoint Test HX.
P144C - Evaporative Emission System Purge Check Valve Performance
Description: The EVAP check valve test is performed during minimal boost conditions, once per drive cycle, when entry
conditions are met. This DTC sets when the fuel tank pressure exceeds a calibrated amount within a specified amount of time during the test.
Possible Causes: • Restricted EVAP ejector connections at the intake air system
• Stuck open EVAP check valve
• Stuck closed EVAP check valve
• Damaged EVAP ejector
• Damaged EVAP check valve
Diagnostic Aids:
Application Key On Engine Off Key On Engine Running Continuous Memory
All GO to Pinpoint Test HX.
P1450 - Unable To Bleed Up Fuel Tank Vacuum
Description: This DTC sets when the evaporative emission (EVAP) running loss monitor detects excessive fuel tank vacuum
with the engine running, but not at idle.
Possible Causes: • EVAP purge valve stuck open
• Blockages or kinks in the EVAP canister tube or EVAP canister purge outlet tube between the fuel tank,
the EVAP purge valve and the EVAP canister
• Fuel filler cap stuck closed, preventing vacuum relief (if equipped)
• Capless fuel tank filler pipe damaged, preventing vacuum relief (if equipped)
• Contaminated fuel vapor elbow on the EVAP canister
• Restricted EVAP canister
• EVAP canister vent valve stuck partially or fully closed
• Plugged EVAP canister vent valve filter
• VREF circuit open
• Damaged FTP sensor
Diagnostic Aids: Visually inspect the EVAP canister inlet port, EVAP canister vent valve filter, and EVAP canister vent hose
assembly for contamination or debris. Check EVAP purge valve for vacuum leak.
Application Key On Engine Off Key On Engine Running Continuous Memory
All GO to Pinpoint Test HX.
P1500 - Vehicle Speed Sensor (VSS)
Description: This DTC sets when a VSS concern interferes with other on board diagnostic (OBD) tests, such as the catalyst
efficiency monitor, the EVAP monitor or the HO2S monitor. Presence of this DTC indicates the VSS input signal was intermittent.
Possible Causes: • Intermittent VSS connections
• VSS harness circuits intermittent open
• VSS harness circuits intermittent short
• Damaged VSS
Diagnostic Aids: Check the wiring, connector, and sensor for damage.
Application Key On Engine Off Key On Engine Running Continuous Memory
F-650 / F-750, GO to Pinpoint Test DF. F-Series Super Duty, Fiesta, Fusion, KA, Motorhome / Stripped Chassis / Step Van
Manual Transmission GO to Pinpoint Test DP.
2016 Powertrain Control/Emissions Diagnosis, Gasoline Engines, 3/2015
2016 Mustang workshop publication supplied to Mustang Atlas. Original technical text and illustrations; HTML formatting by Mustang Atlas. Source page numbering is retained for traceability. Follow the configuration, revision, warnings, and cross-references in the material. About this edition.