P0442 on a 2017 Honda Civic
EVAP Small Leak Detected
P0442 on a 2017 Honda Civic indicates evap small leak detected. It usually stays drivable short-term but should be diagnosed promptly. The most common cause is loose, worn, or cross-threaded fuel cap (typically $15–$60). Confirm the root cause before replacing parts.
What does P0442 mean on a 2017 Honda Civic?
P0442 is set when the EVAP system's small-leak monitor detects an opening approximately 0.040 inches (1.0 mm) or larger. This is the equivalent of the gas cap being left slightly loose or a small crack in a vent hose. The vehicle remains fully drivable and consumes no extra fuel, but the EVAP system can no longer hold the sealed vacuum required for compliance.
This guide covers P0442 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 P0442?
In most cases a 2017 Honda Civic stays drivable for short trips with P0442 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 P0442 on a 2017 Honda Civic?
- Check Engine Light is illuminated
- Faint fuel smell, especially after refueling on a hot day
- No noticeable change in drivability or fuel economy
- Vehicle will fail emissions / smog testing
What causes P0442 on a 2017 Honda Civic?
| Cause | Likelihood | Estimated repair (USD) |
|---|---|---|
| Loose, worn, or cross-threaded fuel cap | Most common | $15–$60 |
| Aged or split EVAP hose | Common | $30–$200 |
| Failing purge or vent valve seal | Common | $80–$350 |
| Cracked EVAP charcoal canister | Occasional | $200–$600 |
| Damaged O-rings at hose-to-canister or hose-to-solenoid connections | Occasional | $20–$120 |
| Pinhole or seam leak in the fuel filler neck | Occasional | $150–$600 |
| Failed fuel tank vent at the tank top (less accessible to inspect) | Rare | $300–$900 |
How to diagnose this on a 2017 Honda Civic
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Tighten or replace the fuel cap
Remove and reinstall the fuel cap to at least three clicks. Inspect the rubber gasket for cracks, debris, or compression set. Replace with an OEM-spec cap if the gasket is damaged or the cap is more than 8 years old.
Tools: None
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Smoke-test the EVAP system
A 0.040-inch leak is too small to find by ear and almost always too small to see visually without smoke. Pressurize the EVAP system with smoke at the service port and trace the smoke trail to its source. Common leak points: behind the rear bumper near the canister, the hose between purge valve and intake, and the top of the fuel tank.
Tools: EVAP smoke machine, UV dye (optional), Inspection mirror and flashlight
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Inspect the EVAP service port itself
The green EVAP service port cap is a frequent leak point because its O-ring hardens and fails after years of heat cycles. With smoke already in the system, watch the service port specifically.
Tools: Inspection mirror
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Visually inspect the charcoal canister
Many trucks and SUVs mount the canister behind the rear axle where it is exposed to road debris and salt spray. Cracks in the plastic housing are common on aging vehicles. Replace the canister if cracked or saturated.
Tools: Floor jack and stands, Trim panel tools
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Verify monitor completion before re-testing
After repair, drive 2–4 cold-start drive cycles with the tank between 25 % and 75 % full. Use a scan tool to confirm the EVAP readiness flag turns "ready." Clearing the code prematurely will set the light again as soon as the monitor runs.
Tools: Scan tool with readiness monitor display
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.
- ENGINE Jul 28, 2025
Service Bulletin - Oil leak at timing chain tensioner inspection cover due to possible insufficient sealant adhesion on inspection cover.
NHTSA #11021745 - FUEL/PROPULSION SYSTEM Aug 6, 2024
Dealer Message - American Honda Motor Co., Inc. (AHM) is searching for certain 2018-2020 Accords, 2016-2020 Civics, 2017-2020 CR-Vs, & 2018-2020 Odysseys that have been diagnosed to be in need of the low-pressure fuel pump, fuel strainer, fuel meter or fuel tank replacement.
NHTSA #11006249 - FUEL/PROPULSION SYSTEM Jul 22, 2024
Dealer Message - American Honda Motor Co., Inc. (AHM) is searching for certain 2018-2020 Accords, 2016-2020 Civics, 2017-2020 CR-Vs, & 2018-2020 Odysseys that have been diagnosed to be in need of the low-pressure fuel pump, fuel strainer, fuel meter or fuel tank replacement. If you have a vehicle that match the qualifiers listed below, AHM requests to have the photos of the lock ring & the low-pressure fuel pump flange taken & sent to TIS (click HERE for example photos).
NHTSA #11005271 - FUEL/PROPULSION SYSTEM Jul 6, 2024
Dealer Message - Dealer Message - American Honda Motor Co., Inc. (AHM) is searching for certain 2018-2020 Accords, 2016-2020 Civics, 2017-2020 CR-Vs, & 2018-2020 Odysseys that have been diagnosed to be in need of the low-pressure fuel pump, fuel strainer, fuel meter or fuel tank replacement.
NHTSA #11004264 - VISIBILITY/WIPER Jun 19, 2024
Service Bulletin - Due to a new North America regulation which introduces a new refrigerant and oil requirement, the compressor shaft seal may leak. American Honda is extending the warranty on the A/C compressor shaft seal from the original 3 years to 10 years from the original date of purchase, with no mileage limitation. The new refrigerant and oil may cause swelling of the compressor shaft seal. The swelling may lead to abnormal wearing of the seal which may increase seal gaps around the compressor shaft allowing refrigerant to leak out.
NHTSA #11002711 - VISIBILITY/WIPER Jun 19, 2024
Service Bulletin - American Honda is extending the warranty on the A/C condenser to 10 years from the original date of purchase with unlimited miles. This warranty extension only covers vehicles that have a defective A/C condenser from the factory. The A/C condenser was not manufactured to specification. As a result, corrosion may develop in the form of tiny holes in the condenser tube walls that allow the refrigerant to leak out.
NHTSA #11002705
+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.
- 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 P0442 on a 2017 Honda Civic?
- Replace the fuel cap
- Replace cracked EVAP hoses and aged O-rings
- Replace the EVAP purge valve or vent valve
- Replace the charcoal canister assembly
- Replace the fuel filler neck (rust or pinhole)
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.
P0442 vs P0455 vs P0456
The three EVAP leak codes describe the same kind of fault at different leak sizes:
| Code | Leak size threshold | Typical real-world cause |
|---|---|---|
| P0456 | ~0.020” (very small) | Cap O-ring, fresh hose pinhole |
| P0442 | ~0.040” (small) | Loose cap, aging hose, cracked vent valve seal |
| P0455 | ~0.090”+ (large or no seal) | Missing cap, disconnected hose, large canister crack |
A vehicle that sets P0456 today often sets P0442 in a few months as the same crack grows.
Why smoke testing is non-negotiable
EVAP leaks are usually too small to find any other way. A bare-eye inspection of every hose and joint will miss most P0442 causes. The smoke machine is a one-time tool purchase (or one-time shop diagnostic fee) that pays for itself on the first EVAP repair.
What “0.040 inch leak” actually means
OBD-II EVAP monitors do not measure the leak directly. They apply a calibrated vacuum or pressure to the sealed system and time how quickly it bleeds off. The leak-equivalent diameter is calculated from that decay rate. A real-world 0.040” hole and a 0.030” hole with a smaller restriction upstream can produce the same monitor result.
P0442 on a 2017 Honda Civic: frequently asked questions
What does diagnostic trouble code P0442 mean on a 2017 Honda Civic?
P0442 is set when the EVAP system's small-leak monitor detects an opening approximately 0.040 inches (1.0 mm) or larger. This is the equivalent of the gas cap being left slightly loose or a small crack in a vent hose. The vehicle remains fully drivable and consumes no extra fuel, but the EVAP system can no longer hold the sealed vacuum required for compliance.
What are the symptoms of P0442 on a 2017 Honda Civic?
Check Engine Light is illuminated. Faint fuel smell, especially after refueling on a hot day. No noticeable change in drivability or fuel economy. Vehicle will fail emissions / smog testing
What causes P0442 on a 2017 Honda Civic?
Loose, worn, or cross-threaded fuel cap (most-common). Aged or split EVAP hose (common). Failing purge or vent valve seal (common). Cracked EVAP charcoal canister (occasional). Damaged O-rings at hose-to-canister or hose-to-solenoid connections (occasional). Pinhole or seam leak in the fuel filler neck (occasional). Failed fuel tank vent at the tank top (less accessible to inspect) (rare)
Is it safe to drive a 2017 Honda Civic with P0442?
In most cases a 2017 Honda Civic stays drivable for short trips with P0442 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.