Diagnostic article Generic OBD-II
P2451: Ford hybrid EVAP test can mislead unless the fuel-door sequence is followed
Ford SSM 48301 explains a software conflict that can distort the EVAP pinpoint test used for P2451 on listed hybrids.
Read before applying this article
Documented application
Ford SSM 48301: 2013–2017 C-MAX Energi, 2017–2018 C-MAX Hybrid, 2013–2020 Fusion Energi, 2017–2020 Fusion/MKZ Hybrid; correction to PC/ED pinpoint test HX22 for listed EVAP DTCs including P2451.
The code alone does not identify a failed part or establish that a vehicle is safe to drive. Confirm the vehicle, reporting module and applicable service procedure.
The bulletin corrects a test condition
The generic P2451 description concerns an EVAP switching valve stuck closed. Ford SSM 48301 does not identify a universal bad valve. Instead, it warns that an internal PCM software conflict can produce incorrect results during pinpoint test HX for this code and several related EVAP faults.
The affected groups listed are 2013–2017 C-MAX Energi, 2017–2018 C-MAX Hybrid, 2013–2020 Fusion Energi and 2017–2020 Fusion/MKZ Hybrid vehicles with an illuminated malfunction indicator lamp. The different year ranges matter; a model name alone is insufficient to apply the instruction.
Why step HX22 needs its own setup
Immediately before HX22, the message requires the fuel door to be fully latched and then opened using its release button. It must remain open while HX22 is completed and be fully latched again before the remaining testing continues. This is a specific sequence within the manufacturer’s pinpoint test, not a general method of resetting P2451.
Simply finding the door already open does not reproduce the stated sequence. Likewise, leaving it open for all later steps would not follow the bulletin. These distinctions explain why a previous apparent failed test may need reassessment before a replacement decision is accepted.
A technician should establish which revision of the diagnostic procedure was used and whether this condition was controlled when HX22 was performed. The message supplies neither a confirmed failed component nor a blanket software-update remedy. If the code persists after correctly conducted testing, the applicable diagnostic path still determines the repair. Do not treat fuel-door operation alone as evidence that the EVAP fault has been fixed.
Source and applicability
Ford SSM 48301: 2013–2017 C-MAX Energi, 2017–2018 C-MAX Hybrid, 2013–2020 Fusion Energi, 2017–2020 Fusion/MKZ Hybrid; correction to PC/ED pinpoint test HX22 for listed EVAP DTCs including P2451.
Article source documents
Source checks describe how the text was prepared; they do not certify a diagnosis or confirm compatibility with every vehicle using this code.
Original code reference
Dictionary definition
EVAP System Switching Valve Stuck Closed
This definition retains its original catalog scope. The article above is limited to its explicitly documented application.
Reference scope
Generic OBD-II definition.
A manufacturer label does not establish the model, year, engine or module to which a diagnosis applies. Read the safety and diagnostic limits.
Definition source
- DTC Database: pinned community code definitions
Source checked · MIT