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P0455 on a 2017 Honda Civic

EVAP Large or Gross Leak Detected

P0455 on a 2017 Honda Civic indicates evap large or gross leak detected. It usually stays drivable short-term but should be diagnosed promptly. The most common cause is missing, loose, or wrong-fit fuel cap (typically $0–$60). Confirm the root cause before replacing parts.

Severity: low Safe to drive (short term) Compact Sedan 2015-2019 Honda Civic

Reviewed by MECH AI Editorial · Last verified · Includes 20 active NHTSA TSBs

What does P0455 mean on a 2017 Honda Civic?

P0455 is set when the EVAP system's gross-leak monitor detects an opening approximately 0.090 inches (2.3 mm) or larger — or in many cases, no seal at all. This is the size of a missing gas cap, a disconnected hose, or a failed vent solenoid stuck open. The system cannot hold pressure or vacuum for the calibration period, so the ECM concludes a major leak.

This guide covers P0455 across the 2015-2019 Honda Civic generation — the symptoms, causes, and diagnostic steps below apply to every model year from 2015 through 2019.

Is it safe to drive a 2017 Honda Civic with P0455?

In most cases a 2017 Honda Civic stays drivable for short trips with P0455 active, but diagnose and repair it promptly. This is a low-severity code — ignoring it can lead to further damage or a failed emissions test.

What are the symptoms of P0455 on a 2017 Honda Civic?

What causes P0455 on a 2017 Honda Civic?

Cause Likelihood Estimated repair (USD)
Missing, loose, or wrong-fit fuel cap Always check first. A locking gas cap from another vehicle that almost fits is a common source. Most common $0–$60
Disconnected or split EVAP hose Common $30–$200
EVAP vent valve stuck open (will not seal during the monitor test) Common $80–$350
Damaged or rusted-through fuel filler neck Occasional $200–$700
Cracked or broken EVAP charcoal canister Occasional $200–$600
Damaged O-ring at the fuel pump assembly cover Rare $30–$500
Rodent damage to EVAP hoses (parked vehicles) Occasional $30–$200

How to diagnose this on a 2017 Honda Civic

  1. Check the gas cap is present and correctly seated

    Confirm the cap is the correct OEM cap for the vehicle. Many generic-fit replacement caps look identical but have slightly wrong gasket geometry. Hand-tighten to at least 3 clicks. Some vehicles flag a missing cap as P0455 within one drive cycle.

    Tools: None

  2. Visually inspect the EVAP hoses near the canister

    On most trucks and SUVs the EVAP canister sits behind the rear bumper or above the rear axle. Inspect every hose from the canister to the tank vent and to the purge solenoid. Pay particular attention to rodent damage on parked vehicles.

    Tools: Floor jack and stands, Flashlight

  3. Smoke-test the EVAP system at low pressure

    Introduce smoke at 0.5 psi through the service port. With a large leak the smoke will pour visibly from the failure point within seconds. If smoke escapes from the vent solenoid even with the solenoid commanded closed, replace the solenoid.

    Tools: EVAP smoke machine

  4. Test the EVAP vent valve function

    Disconnect the vent valve and apply 12 V — it should click and close. Hold a hand vacuum pump to one port and verify the valve holds vacuum when energized. A vent valve that does not close fully will set P0455 because the system can never seal.

    Tools: 12 V test source, Hand vacuum pump

  5. Inspect the fuel filler neck and tank-top seals

    Rust-belt vehicles often develop pinholes or seam separation in the metal portion of the fuel filler neck. Once the rust is through, the EVAP system cannot hold any vacuum. Replacement is the only fix.

    Tools: Floor jack and stands, Inspection mirror

Known Technical Service Bulletins for the 2015-2019 Honda Civic

Manufacturers publish Technical Service Bulletins (TSBs) when a known issue affects a specific vehicle. These bulletins come from the NHTSA database for your Honda Civic.

+14 more TSBs available in MECH AI's TSB explorer for this vehicle.

NHTSA complaints & recalls for the 2017 Honda Civic

Owner-reported safety complaints and official recalls filed with the U.S. National Highway Traffic Safety Administration for the 2017 Honda Civic. Use these to gauge how common a problem is on your specific vehicle before you start chasing Honda Civic diagnostics.

569 owner complaints
22 involved a crash
6 involved a fire
11 reported injuries
  • ENGINE 65
  • STEERING 161
  • UNKNOWN OR OTHER 160
  • ELECTRICAL SYSTEM 99
  • SERVICE BRAKES 35

6 active recalls

  • STEERING:ELECTRIC POWER ASSIST SYSTEM Sep 2018

    Honda (American Honda Motor Co.) is recalling certain 2017-2018 Honda Civic and CR-V vehicles. The magnet that controls the torque sensor output signal for the electronic power steering system may not be properly secured, allowing the magnet to become dislodged. During a full…

    NHTSA campaign 18V663000
  • EQUIPMENT:OTHER:OWNERS/SERVICE/OTHER MANUAL Nov 2018

    Honda (American Honda Motor Co.) is recalling certain 2017-2018 Honda Civic Hatchback and Civic Type R vehicles. The owners guide in these vehicles may not have been included or if included, the owner's guide may not have been properly provided required information. As such, t…

    NHTSA campaign 18V817000
  • AIR BAGS Apr 2018

    Honda (American Honda Motor Co.) is recalling certain 2017 Honda Civic Hatchback and Civic Type R vehicles. Driver and front passenger seatback pads sold as replacement service parts were made without slit openings for the seat-mounted side air bags. In the event of a crash nece…

    NHTSA campaign 18V266000
  • POWER TRAIN:DRIVELINE:DRIVESHAFT Nov 2017

    Honda (American Honda Motor Co.) is recalling certain 2017 Honda Civic Sedan and Coupe vehicles. The right halfshaft may have been improperly heat treated, reducing its strength.…

    NHTSA campaign 17V706000

How do I fix P0455 on a 2017 Honda Civic?

About the 2015-2019 Honda Civic

The 2015-2019 Honda Civic was commonly sold with the following powertrains: 2.0L I4, 1.5L Turbo I4, 1.8L I4. Common trims include LX, Sport, EX, Touring.

How fast P0455 sets after a missing cap

Most OBD-II vehicles flag P0455 within one cold-start drive cycle after the cap is left off. Some Ford and GM vehicles will set a more specific “check fuel cap” message first and only escalate to P0455 if the issue persists across multiple drive cycles.

P0455 right after winter on a parked vehicle

Mice and rats chew EVAP hoses to nest inside the canister or near the fuel tank. If P0455 appears on a vehicle that has been parked for the winter, inspect every accessible EVAP hose for clean-edged bite marks before buying parts. This pattern is so common on rural-parked trucks that several shop forums have dedicated threads.

The cap that “fits” but doesn’t seal

A locking gas cap from a similar-vintage vehicle in the same brand family often threads on but seals against the filler neck at the wrong depth or angle. The result is repeated P0455 codes after every refuel. If the cap has been replaced and the code persists, double-check it is the exact OEM part number for this vehicle.

P0455 on a 2017 Honda Civic: frequently asked questions

What does diagnostic trouble code P0455 mean on a 2017 Honda Civic?

P0455 is set when the EVAP system's gross-leak monitor detects an opening approximately 0.090 inches (2.3 mm) or larger — or in many cases, no seal at all. This is the size of a missing gas cap, a disconnected hose, or a failed vent solenoid stuck open. The system cannot hold pressure or vacuum for the calibration period, so the ECM concludes a major leak.

What are the symptoms of P0455 on a 2017 Honda Civic?

Check Engine Light is illuminated. Distinct fuel smell, especially after refueling. Fuel-cap warning message on the dashboard on some vehicles. No drivability issue. Vehicle will fail emissions / smog testing

What causes P0455 on a 2017 Honda Civic?

Missing, loose, or wrong-fit fuel cap (most-common). Disconnected or split EVAP hose (common). EVAP vent valve stuck open (will not seal during the monitor test) (common). Damaged or rusted-through fuel filler neck (occasional). Cracked or broken EVAP charcoal canister (occasional). Damaged O-ring at the fuel pump assembly cover (rare). Rodent damage to EVAP hoses (parked vehicles) (occasional)

Is it safe to drive a 2017 Honda Civic with P0455?

In most cases a 2017 Honda Civic stays drivable for short trips with P0455 active, but it should be diagnosed and repaired promptly — this is a low-severity code. Ignoring it can lead to further damage or a failed emissions test.

Related diagnostic codes

P0455 on other Honda Civic model years