P0451 on 2014-2018 Kia Soul: EVAP Pressure Sensor Causes and Fixes

What's Unique About the 2014-2018 Kia SOUL

For the second-generation Kia Soul (2014-2017 models in particular), code P0451 is specifically addressed in Technical Service Bulletin FUE038_R1. When this code appears with the symptom of the fuel pump nozzle shutting off early during refueling, the TSB explicitly directs technicians *not* to replace the Canister Close Valve (CCV). Instead, the prescribed repair is to replace a component called the 'Air Drain Case' located near the fuel filler neck, which is prone to causing this venting issue.

Diagnostic Flowchart

Tap your situation to follow the diagnostic path that matches what you're seeing on this vehicle.

Symptoms You May Notice

• Check Engine Light is on
• Difficulty filling the fuel tank (gas pump nozzle clicks off repeatedly).
🎬 Watch: Simple EVAP checks to see why your tank won't fill.
• Slightly reduced fuel economy.
• A faint smell of gasoline vapors may be present.

Most Likely Causes

1. Faulty Fuel Tank Pressure Sensor (FTPS) 🔴 High Probability This is the component directly monitored by the code. Over time, the sensor's internal electronics can fail or drift out of their specified range. It is the most common cause when refueling issues are not present.
   How to confirm: The sensor is on top of the fuel pump assembly, under the rear seat. 🎬 See this walkthrough for locating and replacing the pressure sensor. A technician can monitor its voltage with a scan tool to see if it's reporting pressure changes correctly. If voltage is stuck or erratic, it's bad. A common DIY approach is to replace it due to its high failure rate and relatively low cost.
   Typical fix: Replace the Fuel Tank Pressure Sensor.
   Est. part cost: $30-$115
2. Faulty or Blocked Air Drain Case 🟡 Medium Probability This is the specific part identified in TSB FUE038 as the cause for P0451 when accompanied by refueling difficulty. It is a component of the fuel filler neck assembly that can become blocked or fail, preventing the tank from venting properly during refueling.
   How to confirm: Confirm the symptom of the gas pump clicking off repeatedly is present along with code P0451. The TSB procedure involves removing the rear driver's side wheel and wheel guard to access and replace the case.
   Typical fix: Replace the Air Drain Case.
   Est. part cost: $15-$40
3. Faulty or Sticking Canister Close Valve (CCV) ⚪ Low Probability While a sticking CCV can cause EVAP system pressure issues, Kia has specifically advised against replacing it for the common P0451/refueling problem. It should only be considered if the Air Drain Case has been ruled out or if other codes like P0449 are present without refueling issues.
   How to confirm: The valve can be tested by applying 12V power to see if it clicks open and closed. A smoke test can also reveal if the valve is failing to vent properly.
   Typical fix: Replace the Canister Close Valve.
   Est. part cost: $40-$90
4. Damaged or Clogged EVAP Hoses/Lines ⚪ Low Probability Road debris or physical damage can crack or disconnect the plastic and rubber lines that run from the fuel tank to the charcoal canister and purge valve. A user on a Kia Stinger forum reported a P0451 code after running over a blanket that damaged EVAP components underneath the car.
   How to confirm: Visually inspect all accessible EVAP hoses for cracks, brittleness, or loose connections. A smoke test is the most effective way to find a hard-to-see leak.
   Typical fix: Replace the damaged section of hose.
   Est. part cost: $10-$50

Rare But Worth Checking

• Faulty Purge Control Solenoid Valve (PCSV): While less common for P0451 specifically, a malfunctioning purge valve can sometimes cause erratic pressure readings in the system. It's more often associated with other codes like P0441. A Kia Soul owner on Reddit discussed replacing this part to resolve a check engine light.
• Damaged Charcoal Canister: If the vehicle is frequently over-filled with fuel, liquid gasoline can saturate the charcoal canister, causing blockages and pressure problems. This is an expensive part to replace, so it should be confirmed as the cause before replacement.

Diagnosis Steps

1. Read the code with an OBD-II scanner and note any other codes.
2. Crucial Symptom Check: Determine if you are experiencing difficulty refueling (gas pump clicks off).
3. If refueling issues ARE present: The likely cause is the Air Drain Case per TSB FUE038. The repair involves removing the driver's side rear wheel and wheel guard to access and replace the case, which is attached to the fuel filler neck. Do NOT replace the CCV first.
4. If refueling issues are NOT present: The most likely cause is a faulty Fuel Tank Pressure Sensor (FTPS).
5. To access the FTPS, remove the rear seat cushion (it often pulls up from a front latch) and pry off the black metal service cover.
6. Visually inspect the wiring and connector for the FTPS on top of the fuel pump assembly for damage or corrosion.
7. With a capable scan tool, monitor the FTPS voltage. It should change in response to pressure changes (e.g., when opening the gas cap). If the voltage is stuck, reads 0, or is erratic, the sensor has failed.
8. If the sensor seems to work and no refueling issue is present, perform a visual inspection of all EVAP hoses between the canister, purge valve, and tank.
9. If no obvious faults are found, a smoke test is the definitive method to check the entire EVAP system for small leaks or blockages.

Parts You'll Likely Need

• Fuel Tank Pressure Sensor — This is the most common failure point for a P0451 code when refueling issues are absent. It is located on the fuel pump assembly and often sold separately by aftermarket suppliers.
  Trusted brands: Standard Motor Products, Vemo, Wells, GPD
  OEM price range: $90-$120
  Aftermarket price range: $30-$90
• Air Drain Case (OEM #31035-2K500) — This is the specific part Kia identifies in TSB FUE038 to fix P0451 when accompanied by difficulty refueling. It is part of the filler neck assembly.
  Trusted brands: Genuine Kia
  OEM price range: $15-$40
• Canister Close Valve (OEM #314533K600) — A potential, but less likely, cause. It should not be the first part replaced if refueling issues are the main symptom. Aftermarket versions like the Dorman 911-545 are available.
  Trusted brands: Genuine Kia, Dorman
  OEM price range: $60-$90
  Aftermarket price range: $40-$70

Related Codes That Often Appear With This One

• P0449 — This code for the EVAP Vent Valve/Solenoid Circuit is specifically mentioned alongside P0451 in Kia's TSB FUE038, indicating a related failure in the venting portion of the system that is resolved by replacing the Air Drain Case.
• P0461 — This code relates to the Fuel Level Sensor. Since both the fuel level sensor and the fuel tank pressure sensor are part of the fuel pump assembly, a problem with the assembly or its wiring can sometimes trigger both codes, as shown in a YouTube repair video.

Technical Service Bulletins (TSBs) & Recalls

• TSBFUE038_R1: The definitive TSB for P0451 with refueling issues. Specifies replacing the 'Air Drain Case' and not the CCV. Applies to Soul, Rio, and Forte models.
• TSBFUE038: An earlier version of the same TSB, also linking P0451 to refueling issues on 2014-2017 Soul models.

Platform-Specific Known Issues

• A Technical Service Bulletin (TSB FUE038_R1) was issued for 2014-2017 Kia Soul models that experience early fuel shut-off and illuminate the check engine light with codes P0449 or P0451. The bulletin explicitly states to replace the 'Air Drain Case' (P/N: 31035-2K500) near the fuel filler neck and warns technicians *not* to replace the Canister Close Valve for this condition.

Mechanic-Grade Diagnostic Values

• Fuel Tank Pressure Sensor (FTPS) signal voltage — expected: Approximately 2.5V with key on, engine off, and gas cap removed (atmospheric pressure).. Failure: Voltage is stuck (e.g., at 0V or 5V), does not change, or reads outside the expected 2.5V range at atmospheric pressure. When a slight vacuum is applied with a hand pump, voltage should decrease. If it doesn't, the sensor is faulty.
• Purge Control Solenoid Valve (PCSV) coil resistance — expected: Approximately 26.2 Ohms.. Failure: Resistance is significantly higher, lower, or shows an open circuit (infinite resistance).

Scan Tool Commands That Help

• Kia GDS (Global Diagnostic System): Actuation Test — To manually command the Canister Close Valve (CCV) and Purge Control Solenoid Valve (PCSV) to open or close. This verifies the solenoid is functioning electrically and can help isolate blockages or leaks.
• Kia GDS (Global Diagnostic System): Reset adaptive values — After replacing a component like the FTPS or PCSV, this special function can be used to clear the ECM's learned fuel trim and other values, which may help resolve performance issues more quickly.
• Advanced OBD2 Scanner: EVAP System Test (Active Test) — This function on many professional-grade scanners allows the user to command the vent and purge valves to seal the system and monitor pressure changes, helping to verify the function of individual components without the dealer-specific GDS tool.

Wiring & Ground Locations

• ECM Connector Pin 26 — At the Engine Control Module (ECM).. This is the specific pin where the signal from the Fuel Tank Pressure Sensor (FTPS) is received by the ECM. It can be back-probed to test the sensor's voltage output directly at the computer, helping to rule out wiring issues between the sensor and the ECM.
• Fuel Pump Assembly Connector — On top of the fuel pump assembly, accessible under the rear seat cushion.. This is the primary connection point for the FTPS. The three wires for the sensor (5V reference, ground, and signal) can be tested here for power, ground integrity, and signal output before condemning the sensor itself.

Real Owner Repair Stories

• YouTube channel 'B khmer' (2010 Kia Soul 1.6L) — Check Engine Light with codes P0451 (EVAP Pressure Sensor Range) and P0461 (Fuel Level Sensor Abnormal).
  ✅ What actually fixed it The owner replaced the entire fuel pump assembly, which contains both the Fuel Tank Pressure Sensor and the Fuel Level Sensor. This resolved both codes simultaneously.
• YouTube channel 'Brian Balatbat' (2010 Kia Soul 1.6L) — Check Engine Light with code P0451. The light would return within 20 miles of being reset.
  ❌ Tried (didn't work) Resetting the code.
  ✅ What actually fixed it The owner replaced only the Fuel Tank Pressure Sensor located on top of the fuel pump assembly. This was a direct fix for the isolated P0451 code.

Model Year Variations Within This Range

• 2014 - March 6, 2017: Models produced in this range are subject to Technical Service Bulletin FUE038_R1, which identifies the 'Air Drain Case' as the likely cause for P0451 when it occurs with difficulty refueling. Models produced after this date are not covered by this specific TSB.