P0455 on 2020-2022 Ford Explorer 2.3L: EVAP Gross Leak Causes and Fixes

What's Unique About the 2020-2022 Ford Explorer

Unlike many vehicles where P0455 points to a loose gas cap or a bad purge valve, the 2020-2022 Explorer with the 2.3L engine has a well-documented, specific electrical issue. Ford has issued multiple Technical Service Bulletins (TSBs) identifying a wiring harness connector, known as C1198, as a frequent cause of this code. This fault often triggers a cluster of other EVAP and fuel system codes because it disrupts shared Voltage Reference (VREF) signals for multiple sensors, making a wiring inspection the top priority over component replacement.

Symptoms You May Notice

• Check Engine Light is on
• A 'Check Fuel Fill Inlet' message may appear on the dashboard.
• Possible faint fuel smell, especially when parked or after refueling.
• Occasional hard starting, though less common than other causes.
• Difficulty starting immediately after refueling (a classic symptom of a stuck-open purge valve).

Most Likely Causes

1. Wiring Harness Issue at Connector C1198 🔴 High Probability Ford TSBs SSM 51247 and SSM 51132 specifically call out this connector for pin fitment and corrosion issues on 2020-2022 Explorers with the 2.3L engine. The connector is in a location prone to moisture and road spray on the driver's side frame rail.
   How to confirm: Visually inspect connector C1198, located on the driver's side lower frame area underneath the brake lines near the Electric Brake Booster (EBB). Check for loose pins, corrosion, or harness damage. This is the prime suspect if codes P04F0, P008A, P0451, P0456, P0496, or P018C are also present. TSB 51247 specifically advises checking the three Voltage Reference (VREF) wires passing through this connector by referencing Wiring Diagram Cell 22-12.
   Typical fix: Repairing the wiring, cleaning the connector terminals, or replacing affected pins. In severe cases, a harness pigtail replacement is needed. The Motorcraft pigtail kit is part number WPT-1198.
   Est. part cost: $20-$75
2. Dirty or Faulty Capless Fuel Filler Inlet 🟡 Medium Probability The capless system relies on a spring-loaded flap to seal. Dirt, debris, or rust on the sealing surface can prevent it from closing properly, creating a large leak.
   How to confirm: Visually inspect the fuel filler opening for any debris, dirt, or damage that could prevent a proper seal. The flap should move freely and close securely. Use the funnel provided with the vehicle to work the mechanism and check for smooth operation. 🎬 Watch: How to properly clean your capless fuel filler neck.
   Typical fix: Clean the filler neck opening with a clean cloth and the vehicle's funnel to work the mechanism. If the seal is damaged or cleaning does not work, the entire fuel filler neck assembly must be replaced.
   Est. part cost: $100-$200
3. Failed Canister Purge Valve ⚪ Low Probability This part can fail and stick open, creating a large vacuum leak. However, Ford TSB SSM 50306 notes that this part is frequently misdiagnosed on these vehicles and should be tested before replacement.
   How to confirm: Remove the valve (located in the engine bay) and try to blow through it when it is electrically disconnected. If air passes through, it is stuck open and has failed. A professional scan tool can also command the valve to open and close to test its function.
   Typical fix: Replacement of the canister purge valve. The OEM part number for the 2.3L engine is often 🎬 See this walkthrough for replacing the 2.3L purge valve and hose. FR3Z-9C915-A (Motorcraft CX2627).
   Est. part cost: $40-$100
4. Cracked or Disconnected EVAP Hose ⚪ Low Probability
   How to confirm: A visual inspection of all EVAP lines from the engine bay to the charcoal canister near the tank may reveal a crack or disconnection. The most effective method is to have a mechanic perform a smoke test, which injects low-pressure smoke into the system to reveal the exact location of any leaks.
   Typical fix: Replacing the damaged section of hose or reconnecting it.
   Est. part cost: $20-$60

Rare But Worth Checking

• Failed EVAP Canister Vent Valve/Solenoid: This valve, located near the charcoal canister by the fuel tank, can get stuck open, causing a large leak. It's less common than the purge valve or wiring issues but is a possible cause.
• Cracked Charcoal Canister: Physical damage to the plastic housing of the charcoal canister from road debris can cause a large leak. This would be easily visible during a visual inspection or smoke test.
• Faulty Fuel Tank Pressure (FTP) Sensor: The FTP sensor itself can fail, sending incorrect data to the ECU and causing a false P0455 code. The wiring for this sensor runs through the problematic C1198 connector, making a wiring fault more likely than a sensor failure.

Diagnosis Steps

1. Scan for Codes: Use an OBD-II scanner. The presence of a cluster of codes (e.g., P0451, P0456, P04F0, P008A, P018C) alongside P0455 is a very strong indicator of the TSB-related wiring issue at connector C1198.
2. Inspect Fuel Filler Inlet: Open the fuel door and carefully inspect the capless filler neck for any dirt, debris, or damage that could prevent a proper seal. Clean it thoroughly with a cloth and the supplied funnel.
3. Inspect Connector C1198: This is the most critical step for this vehicle. Locate connector C1198 on the driver's side lower frame, underneath the brake lines near the electric brake booster. Disconnect it and meticulously inspect for corrosion, water intrusion, or bent/loose pins. Repair any wiring issues found. The pigtail kit WPT-1198 is available for severe damage.
🎬 Watch: A guide to diagnosing P0455 and P0456 codes on your Explorer.
4. Test Canister Purge Valve: If no wiring issues are found, locate the purge valve in the engine bay. Disconnect it electrically and attempt to blow through it. If air passes, the valve is stuck open and needs replacement.
5. Perform Smoke Test: If all previous steps do not reveal the cause, the next step is to perform a low-pressure EVAP smoke test. This involves injecting smoke into the EVAP service port (usually has a green cap) to find physical leaks in hoses, the charcoal canister, or the fuel tank.

Parts You'll Likely Need

• Wiring Harness Connector Pigtail Kit (OEM #WPT-1198) — To fix the common point of failure at connector C1198, as identified in multiple Ford TSBs for this specific vehicle and code.
  Trusted brands: Motorcraft
  OEM price range: $40-$75
  Aftermarket price range: $20-$50
• Canister Purge Valve (OEM #FR3Z-9C915-A (Motorcraft CX2627)) — A potential cause if it fails and sticks open, though it is often misdiagnosed. Test before replacing.
  Trusted brands: Motorcraft, Bosch, Dorman
  OEM price range: $60-$100
  Aftermarket price range: $40-$80
• Fuel Filler Neck (Capless) — Replaced if the sealing flap is damaged or warped, preventing the system from sealing properly after being cleaned.
  Trusted brands: Motorcraft
  OEM price range: $150-$200
  Aftermarket price range: $100-$150

Related Codes That Often Appear With This One

• P0451 — EVAP Pressure Sensor/Switch Range/Performance. This directly points to an electrical issue with the fuel tank pressure sensor circuit, which runs through the C1198 connector.
• P0456 — Indicates a small EVAP leak. It can appear alongside P0455 if the C1198 wiring issue is causing intermittent sensor readings.
• P04F0 — EVAP System Leak Detected (Very Small Leak). Often triggered by the same C1198 wiring fault.
• P008A — Low Pressure Fuel System Pressure - Too Low. This code is also listed in TSB 51247 as being potentially caused by the C1198 connector issue.
• P018C — Fuel Pressure Sensor 'B' Circuit Low. Another code directly linked to the C1198 connector fault in TSB 51247.

Technical Service Bulletins (TSBs) & Recalls

• SSM 51247: Notes that P0455 and other codes (P04F0, P008A, P0451, P0456, P0496, P018C) on 2.3L models may be due to the wiring harness connection at connector C1198 and advises checking VREF wires by referencing Wiring Diagram Cell 22-12.
• SSM 51132: States that multiple DTCs including P0455 on 2020-2022 Explorers with the 2.3L engine may be due to the wiring harness connection at C1198.
• SSM 50306: Advises technicians that many returned canister purge valves test as fully functional, suggesting the part is often misdiagnosed and that full system diagnosis should be performed before replacement.

Platform-Specific Known Issues

• Ford TSBs SSM 51247 and SSM 51132 specifically identify a wiring harness connection at connector C1198 on the driver's side lower frame as a primary cause for P0455 on 2.3L models, often accompanied by other codes.
• TSB 51247 further specifies that three Voltage Reference (VREF) wires run through C1198, explaining why a single connector fault can trigger a wide array of seemingly unrelated DTCs.

Mechanic-Grade Diagnostic Values

• Fuel Tank Pressure (FTP) Sensor Voltage (KOEO) — expected: 2.5V - 3.0V at atmospheric pressure. Failure: A reading near 0V or 5V indicates a sensor or wiring fault. Voltage should decrease as vacuum is applied.
• EVAP Canister Purge Valve Solenoid Resistance — expected: 30 to 38 ohms. Failure: A reading significantly outside this range, or an open/short circuit, indicates a faulty solenoid coil.
• EVAP Canister Vent Solenoid Resistance — expected: 48 to 65 ohms. Failure: A reading outside this range suggests the vent solenoid coil is faulty.
• Voltage Reference (VREF) — expected: 5.0V. Failure: Incorrect voltage on VREF circuits at connector C1198 points to a wiring or PCM issue.

Hidden / Shadow Codes Worth Checking

• Mode $06, Test ID $80: This test ID often corresponds to the large leak (0.040") test. Monitoring the values from this test can show if the system is borderline failing before a code is set. (see via A scan tool capable of displaying Mode $06 data, such as FORScan, Torque Pro, or professional-grade scanners.)

Scan Tool Commands That Help

• Ford IDS or FORScan: EVAP System Leak Test — This is a key bidirectional control used to command the EVAP system to seal itself (by closing the vent valve) and then monitor the FTP sensor for pressure decay. It electronically verifies if a leak is present before performing a physical smoke test.
• Ford IDS or FORScan: Output State Control (OSC) for Purge/Vent Valve — Allows a technician to manually command the purge valve (normally closed) and vent valve (normally open) to open or close, verifying their mechanical and electrical function independently.

Wiring & Ground Locations

• C1198 — On the driver's side lower frame rail, located underneath the brake lines near the Electric Brake Booster (EBB).. This is the main connector identified by Ford TSBs as the primary failure point. It carries multiple VREF, signal, and ground wires for the EVAP and fuel systems, including the FTP sensor.
• Wiring Diagram Cell 22-12 — In the official Ford service manual wiring diagrams.. TSB 51247 specifically directs technicians to this diagram cell to identify the three VREF wires that pass through connector C1198 for the 2.3L engine, which are critical for diagnosis.
• G104 — On the right side of the engine compartment, near the front corner.. This is a major chassis ground point for several engine compartment components. A poor connection here could cause erratic behavior in various systems, although it is not the primary suspect for P0455.

"I Checked Everything" — The Actual Cause

• On the 2020-2022 Explorer, it is common for the EVAP system to pass a smoke test, yet the P0455 code persists. The root cause is frequently electrical, not a physical leak. The issue lies with corrosion or poor pin fitment in the C1198 connector on the driver's side frame rail, which disrupts the voltage reference (VREF) or signal from the Fuel Tank Pressure (FTP) sensor. The PCM interprets the faulty electrical signal as a large leak, even though the system is physically sealed.

OEM Part Supersession History

• FR3Z-9C915-A → This part number for the canister purge valve appears to be current for the specified vehicle range. — N/A

Model Year Variations Within This Range

• 2020: Certain 2020 Ford Explorers with 2.3L engines built between May 27, 2019, and July 17, 2019, were subject to recall 19S32. The main wiring harness may not have been properly secured, allowing it to contact the A/C compressor pulley. This could cause a short circuit, potentially affecting multiple systems, though not directly cited for P0455, it highlights potential wiring vulnerabilities in early-build 2020 models.

Diagnostic Flowchart

Other Known Issues on This Vehicle

Issues unrelated to this code that are worth knowing about as an owner of this generation:

• Rear Axle Mounting Bolt Fracture 🔴 High — Widespread enough to trigger multiple recalls (e.g., 22S27) and a customer satisfaction program (22N06). Affects 2020-2022 models. The bolt can fracture during acceleration, potentially leading to a loss of motive power or a rollaway condition if the parking brake is not engaged. (Ref: Recall 22S27, Customer Satisfaction Program 22N06)
• 360-Degree Camera System Failure 🟠 Medium — Very common, affecting 2020-2023 Explorers and platform mates. The issue often presents as a blue or black screen instead of the camera image. It has led to multiple recalls (e.g., 21V-735, 23S02) as software updates have been iteratively developed. (Ref: Recalls 21V-735, 23S02, 23S48)
• 10-Speed Automatic Transmission Faults 🟠 Medium — Owners report issues like erratic/harsh shifting, delayed engagement, and in some cases, premature failure. The 10R60 transmission used with the 2.3L engine has known software issues and potential internal component problems like CDF drum bushing wear. (Ref: TSB 23-2176 (Delayed Reverse Engagement))
• Water Leaks into Rear Liftgate/Spare Tire Area 🟡 Low — A noticeable number of owners have reported water intrusion in the rear of the vehicle, which can affect audio components. (Ref: TSB 23-2181)

Used vs. New Parts: Buying Guide for This Vehicle

When a used part is the smart pick: For this specific P0455 issue, using used parts is generally not recommended for the most common fixes. The primary cause is a wiring connector (C1198) which should be repaired with a new pigtail (WPT-1198), not a used harness. A used fuel filler neck from a low-mileage, non-corroded vehicle could be a cost-effective option if the sealing flap is the issue.

Donor-vehicle mileage cap: roughly under 50000 miles for the part to have meaningful remaining life.

What to inspect on the donor part:

• For a fuel filler neck: Inspect the sealing flap for free movement and a lack of rust or debris. Ensure the surrounding plastic is not cracked.
• For hoses or canisters: Check for any cracks, brittleness, or signs of physical damage. Ensure all connection points are intact.

OEM-only on this vehicle (don't cheap out):

• Wiring Harness Pigtail (WPT-1198): Given the known TSBs, using the OEM-specified pigtail is critical to ensure proper pin fitment and wire gauge.
• Sensors (FTP Sensor): While aftermarket is available, electronic sensors that communicate with the PCM are often best sourced from OEM (Motorcraft) to avoid compatibility or calibration issues.

Aftermarket brands forum-validated for this vehicle:

• Bosch
• Dorman (for mechanical parts like valves; be cautious with electronics)

Brands owners have reported issues with on this vehicle:

• No-name, unbranded electronic sensors or valves from online marketplaces should be avoided as their quality control and specifications can be inconsistent.

Real Owner Stories

Aggregated from forums and TSBs cited above. Mileages and costs reflect what owners reported in those sources.

Related OBD-II Codes

• P04F0 — Often appears alongside P0455 when there is a wiring harness issue or pin fitment problem at connector C1198.
• P0451 — An EVAP sensor range/performance code that frequently clusters with P0455 due to VREF wire issues in the C1198 harness.
• P018C — Fuel pressure sensor circuit low; identified in TSB 51247 as a code that may trigger simultaneously with P0455 due to shared wiring at the driver's side frame rail.
• P008A — Low pressure fuel system code that can be triggered by the same C1198 connector corrosion affecting EVAP codes.
• P0456 — Small EVAP leak code that often accompanies P0455 when the system integrity is compromised by the capless filler or wiring faults.
• P0496 — High EVAP purge flow; mentioned in TSB 51247 as part of the cluster of codes caused by faulty VREF wires in the main chassis harness.

Frequently Asked Questions