P1449 on 2013-2016 Scion FR-S: EVAP System Clog Causes and Fixes

What's Unique About the 2013-2016 Scion FR-S

The Scion FR-S shares its platform and powertrain with the Subaru BRZ. As such, it uses Subaru's diagnostic logic for this code. The system is known to be sensitive to blockages in the vent filter assembly, which is exposed to road debris and can be a welcoming home for spiders building webs. In areas with heavy winters, ice and snow can also cause a temporary blockage that triggers this code. The issue is so prevalent that Subaru eventually released a redesigned drain filter with a protective cover.

Symptoms You May Notice

• Check Engine Light is on
• Traction control light may also illuminate (common behavior on this platform when a CEL is triggered)
• Gas pump nozzle clicks off repeatedly and frequently during refueling
• No noticeable impact on engine performance or drivability

Most Likely Causes

1. Clogged EVAP Vent Filter / Drain Filter 🔴 High Probability The filter's location in the rear of the vehicle, near the wheel well, exposes it to road dust, debris, and moisture. Its design can also attract spiders, whose webs are a very common cause of the blockage. This is the most frequent reason for P1449.
   How to confirm: Locate the filter assembly near the charcoal canister (above the rear differential/subframe area). It's a small plastic box. Disconnect the hose and the filter. Attempt to blow air through it; if it's difficult or impossible, it's clogged. Visually inspect the inlet and outlet for spider webs or packed dirt.
   Typical fix: Remove the filter and clean it with low-pressure compressed air by tapping it on a hard surface to dislodge dust. If it's saturated with fuel or cannot be cleared, it must be replaced. Consider replacing with the redesigned part mentioned in TSB 11-205-25R for a more permanent solution.
   Est. part cost: $30-$60
2. Blocked EVAP Vent Hoses 🟡 Medium Probability The same debris, spider webs, or ice that can clog the filter can also block the rubber hoses leading to and from it. An underbody car wash can also sometimes force water into the vent hose, causing a temporary clog.
   How to confirm: Remove the hoses connected to the vent filter and charcoal canister. Visually inspect them for blockages or kinks. Blow compressed air through them to ensure they are clear.
   Typical fix: Clear the blockage with compressed air. If the hose is cracked, brittle, or damaged, replace it.
   Est. part cost: $10-$30
3. Saturated Charcoal Canister ⚪ Low Probability This is almost always caused by operator error, specifically, habitually 'topping off' the fuel tank after the pump has already automatically shut off. This forces liquid gasoline into the canister, which is only designed to handle vapor.
   How to confirm: Remove the charcoal canister. If it feels unusually heavy, smells strongly of raw fuel, or has liquid gasoline draining from it, it is saturated and ruined.
   Typical fix: The charcoal canister must be replaced. The new canister will be ruined as well if the habit of overfilling the tank continues. This is a much more expensive repair than a clogged filter.
   Est. part cost: $170-$275

Rare But Worth Checking

• Clogged Drain Separator: The drain separator is another component in the vent line that can become clogged with debris or ice, similar to the vent filter. The factory service manual lists this as a possible point of failure.
• Aftermarket Flex Fuel Kit: Some aftermarket flex fuel kits tap into the EVAP system wiring. If the vehicle's tune is not properly updated to account for this modification, it can lead to the ECU throwing a P1449 code because it no longer sees the expected response from the EVAP system.

Diagnosis Steps

1. Verify the code with an OBD-II scanner.
2. Check for the primary symptom: difficulty refueling. If the gas nozzle clicks off constantly, a vent clog is highly likely.
3. Safely raise the rear of the vehicle and secure it on jack stands.
4. Locate the EVAP system components, typically above the rear subframe and differential. You will see the large charcoal canister and smaller attached components and hoses.
5. Identify the EVAP vent filter (a small plastic box, sometimes called a drain filter) and its connecting hoses. It is often tucked above the rear passenger-side wheel well area.
6. Disconnect the hoses from the filter. Inspect the hose ends and filter ports for spider webs, dirt, or other debris.
7. Attempt to blow through the hoses and the filter separately. The component that restricts airflow is the source of the clog. A YouTube video shows a large amount of dust being knocked out of a clogged filter on a similar Subaru.
8. If a hose is clogged, clear it with compressed air. If the filter is clogged, try cleaning it with compressed air. If it remains clogged or is wet with fuel, replace it. Some owners have had success simply by tapping the filter on the ground to dislodge packed dust.
9. In some cases, access may be tight, and lowering the rear differential slightly may be necessary to gain clearance to remove the filter assembly.
10. If no clog is found in the filter or hoses, the charcoal canister itself may be saturated. This is rare unless the tank is frequently overfilled.
11. After cleaning or replacing the clogged component, reassemble everything, clear the code with the scanner, and drive the vehicle to see if the code returns.

Parts You'll Likely Need

• EVAP Vent Filter / Drain Filter Assembly (OEM #42085FL00B) — This is the most common failure point, as it is designed to filter the air entering the EVAP system and is prone to clogging from dust, debris, and spider webs. Part number 42085FL00B is the redesigned part with a protector mentioned in Subaru TSB 11-205-25R to prevent future clogs.
  Trusted brands: Subaru (OEM)
  OEM price range: $40-$70
  Aftermarket price range: $25-$50
• Charcoal Canister (OEM #SU003-04502) — This part only needs replacement if it has been saturated with liquid fuel from repeatedly overfilling the gas tank.
  Trusted brands: Toyota/Subaru (OEM)
  OEM price range: $200-$275
  Aftermarket price range: $150-$220

Related Codes That Often Appear With This One

• P0453 — P0453 indicates 'EVAP Pressure Sensor/Switch High Input'. A clog in the vent system can cause pressure to build during certain test cycles, which can be interpreted by the sensor as a high input, potentially triggering both codes. An owner on ft86club.com reported experiencing both codes together.

Technical Service Bulletins (TSBs) & Recalls

• Subaru TSB 11-205-25R: DTC P1449 EVAP System Clog Detected / Repair Procedure
• Subaru TSB 11-123-12: Ice and Snow Clogging of Evaporative System Hoses, DTC P1449

Platform-Specific Known Issues

• Subaru issued Technical Service Bulletin (TSB) 11-123-12 for other models, warning that ice and snow buildup during extended highway driving in winter can clog the EVAP hoses and trigger P1449.
• Subaru TSB 11-205-25R addresses P1449 and introduces a redesigned drain filter assembly (Part No. 42085FL00B) with a protector to prevent debris buildup. While this TSB lists newer models, the part and issue are directly relevant.

Mechanic-Grade Diagnostic Values

• EVAP Vent Valve / Drain Valve Solenoid Resistance — expected: 20 to 50 Ohms. Failure: A reading of 0 Ohms indicates a short, while an infinite or 'OL' reading indicates an open circuit. A reading outside the 20-50 Ohm range suggests the coil is failing, even if it hasn't failed completely.
• Voltage to EVAP Vent Valve Connector — expected: Approximately 12V (Battery Voltage). Failure: No voltage at the connector when the key is on points to a wiring issue, fuse, or problem with the ECU's driver circuit.

Scan Tool Commands That Help

• Toyota Techstream / High-End Bidirectional Scanner: Evaporative System Check (Automatic Test Mode) — This function allows a technician to force the vehicle's onboard EVAP monitor to run without waiting for the natural 5-hour 'soak time' after the engine is turned off. It simulates the system monitor and will set a code if a malfunction is detected, making it invaluable for verifying that a repair (like cleaning a clog) has been successful. The test typically takes 8-15 minutes to complete.
• Toyota Techstream / High-End Bidirectional Scanner: Manual EVAP Component Activation — Advanced scan tools can manually command the vent valve (Canister Close Valve or CCV) to open or close. For a P1449 clog, you can command the valve closed and then attempt to blow air through the vent line; if air still doesn't pass, it confirms the clog is in the line or filter, not the valve itself. Conversely, if the valve fails to click or change state when commanded, the valve itself is faulty.

Wiring & Ground Locations

• Canister Pump Module — Under the right rear of the vehicle, near the fuel tank.. This module contains the vent valve (also called a drain valve or canister close valve) and the canister pressure sensor. P1449 is triggered by a clog in the vent path associated with this module. A wiring diagram for a 2014 FR-S confirms its location and connection to the main Engine Control Module (ECM).

Real Owner Repair Stories

• Reddit user on r/GR86 (GR86 (shares platform architecture)) — P1449 code appeared after a side-impact collision to the passenger side rear wheel/quarter panel area. The main symptom was the inability to refuel; the pump would click off after only adding a small amount of fuel.
  ❌ Tried (didn't work) Replacing the vapor canister.
  ✅ What actually fixed it The user was still diagnosing, but the strong implication is that the impact damaged or crushed a component of the EVAP vent system in the rear passenger side of the vehicle, leading to the clog. This highlights that physical damage, not just debris, can cause P1449.
• LegacyGT.com forum user (2016 Subaru Legacy 2.5i) — P1449 code appeared immediately after filling up with gas and going through a car wash.
  ❌ Tried (didn't work) Resetting the code (it came back after two starts)., Checking the gas cap.
  ✅ What actually fixed it The resolution was not posted, but the circumstances strongly suggest that the underbody spray of the car wash forced water into the EVAP vent filter or an attached hose, causing a temporary but complete blockage that the ECU detected as a clog.

OEM Part Supersession History

• Various older filter designs → 42085FL00B — Subaru TSB 11-205-25R introduced a redesigned drain filter assembly that includes an added protector. This protector is designed to prevent the buildup of debris, which is the primary cause of P1449.

Model Year Variations Within This Range

• 2015-2016: For the 2015 model year, the FR-S received an updated engine sub-harness and improved coil packs. While not directly related to the EVAP system, it's a notable change within the generation.
• 2016: The 2016 model year added a standard backup camera and a new 7-inch touchscreen audio system. The powertrain and EVAP system remained unchanged from the 2013 debut.
• 2014+: Vehicles produced after February 2014 had revisions to the dashpad to prevent a common 'double-bump' deformation from heat.

Diagnostic Flowchart

Other Known Issues on This Vehicle

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

• Engine Valve Spring Fracture 🔴 High — Common enough on 2013 models to trigger a major safety recall (Subaru recall WTY-84 / NHTSA 18V772000). Can lead to engine stall or catastrophic failure. (Ref: NHTSA Campaign Number: 18V772000)
• High-Pressure Fuel Pump Chirp/Squeak 🟡 Low — A very common audible annoyance across all model years. Often described as 'crickets' from the engine bay at idle. Caused by the pump design and certain fuel compositions. (Ref: Toyota offered a warranty extension (ZKC) for this issue, replacing the fuel pump assembly.)
• Tail Light Condensation/Water Leak 🟠 Medium — Widespread issue, especially on earlier models (2013-2014), due to a poor factory gasket design between the tail light housing and the car body. (Ref: Toyota TSB S-SB-0002-13 Rev1)
• Clutch Release Bearing Failure 🟠 Medium — A common point of failure on manual transmission cars, especially in cold weather, leading to grinding noises when shifting.
• Post-Recall Engine Failure Concerns 🔴 High — A significant number of owners reported engine failures shortly after having the valve spring recall performed, leading to a class-action lawsuit. The cause was often attributed to improper application of sealant by technicians during the complex repair. (Ref: Related to NHTSA recall 18V772000)

Used vs. New Parts: Buying Guide for This Vehicle

When a used part is the smart pick: For the charcoal canister (Part SU003-04502), a used part can be a cost-effective option if the original failed due to saturation from over-filling the tank. A used canister from a low-mileage, collision-damaged vehicle is likely to be perfectly functional.

Donor-vehicle mileage cap: roughly under 80000 miles for the part to have meaningful remaining life.

What to inspect on the donor part:

• For a charcoal canister, ensure there is no smell of raw fuel and no signs of physical damage or cracks.
• The part should feel light; if it feels heavy, it may be saturated with fuel.
• Verify the donor vehicle's mileage and ensure it's from a non-flood vehicle.

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

• EVAP Vent Filter / Drain Filter Assembly: Because the OEM redesigned the part (42085FL00B) to specifically fix the clogging issue that causes P1449, it is highly recommended to use the new OEM part rather than an older used part or an aftermarket part that may not have the updated protective cover.

Brands owners have reported issues with on this vehicle:

• Avoid unbranded, generic EVAP vent filters from online marketplaces, as they are unlikely to feature the updated protective design of the OEM part.

Real Owner Stories

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

Related OBD-II Codes

• P0453 — Evaporative Emission System Pressure Sensor/Switch High Input. This code is explicitly mentioned as appearing with P1449. A clog in the vent system prevents pressure from escaping, causing an abnormally high reading from the pressure sensor.
• P0446 — Evaporative Emission System Vent Control Circuit. A clogged filter (P1449) produces the same symptoms as a vent valve that is stuck closed or has a circuit fault. These codes are closely related during diagnosis as they affect the same function.
• P0451 — Evaporative Emission System Pressure Sensor/Switch Range/Performance. A clog can prevent the EVAP system from achieving the correct vacuum or pressure levels during its self-test, causing the sensor's readings to be out of the expected performance range.
• P0441 — Evaporative Emission Control System Incorrect Purge Flow. A significant blockage in the vent side of the system can disrupt the pressure dynamics when the purge valve opens, potentially leading the ECU to detect an incorrect purge flow rate.

Frequently Asked Questions