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A P1457 code (‘EVAP Control System Leak Detected — Canister Side’) is the close cousin of P1456 (fuel tank side). Both are Honda/Acura-specific EVAP leak codes, and both are detected during the same EVAP system leak test — but P1457 points the finger at the canister side of the EVAP system: the charcoal canister itself, the canister vent shut valve, the purge valve, and the hoses connecting them to the engine.
If you’ve already worked through a P1456 diagnosis and want to understand how P1457 differs, or you’re starting fresh with a P1457 code on your Civic, Accord, CR-V, or Acura, this guide covers the canister-side causes specifically.
What Does P1457 Mean on a Honda?
Honda’s EVAP system uses a two-stage leak test: one portion of the test isolates and checks the fuel tank side of the system (covered by P1456), and another portion checks the canister side — the charcoal canister, the canister vent shut valve (CVS valve), the purge valve, and the lines running to the intake manifold. P1457 sets when this canister-side portion of the test detects a leak (or, in some cases, a vent that isn’t sealing or opening correctly during the test sequence).
Because the canister side of the EVAP system involves more individual components than the fuel tank side, P1457 has a slightly wider range of possible causes — but the diagnostic approach is the same: a methodical check of each component in the canister-side circuit.
Common Causes by Component
Canister Vent Shut Valve (CVS Valve)
The CVS valve sits near the charcoal canister and is responsible for sealing the system during the leak test. It’s one of the most common P1457 culprits:
- Valve stuck open — if the CVS valve doesn’t close fully during the test, the system can’t hold vacuum/pressure, and the ECM reads this as a leak on the canister side.
- Valve stuck closed or restricted — less commonly, a valve that’s stuck closed can prevent the system from venting properly between tests, which can also produce a P1457 under certain conditions.
- Wiring/connector corrosion — the CVS valve is electrically actuated, so a corroded connector or damaged wire can prevent it from responding correctly during the test sequence.
Charcoal Canister
- Cracked canister housing — the plastic canister housing can crack with age, particularly on models where it’s mounted low and exposed to road debris/salt.
- Degraded canister seals — the seals where hoses connect to the canister can harden and crack over time, creating small leaks that are enough to fail the canister-side test.
- Saturated/contaminated canister — if the canister has absorbed fuel (from a failed purge valve or overfilling the tank in the past), it can affect the system’s ability to hold the test pressure correctly.
Purge Valve and Purge Line
- Purge valve leaking when closed — if the purge valve doesn’t seal completely when commanded closed, it creates a path for the canister side to leak into the intake manifold during the test.
- Cracked purge line hose — the rubber/plastic hose connecting the purge valve to the intake manifold is a common crack point, especially in engine bays that run hot.
Model-Specific Notes
- 8th-gen Civic (2006-2011) — CVS valve and canister seals are the most frequently reported causes.
- 8th-gen Accord (2008-2012) and Acura TSX — shares much of the same EVAP architecture as the Civic; CVS valve issues are common here too.
- CR-V (3rd/4th gen) — canister mounting location (closer to the rear of the vehicle, near the fuel tank) makes it more exposed to road salt and debris, increasing the chance of housing cracks over time.
- Acura RDX/TL — similar canister-side architecture; purge valve leaks are a relatively common finding on these models.
Symptoms of P1457
- Check Engine Light with P1457 stored (sometimes alongside P1456 if both portions of the EVAP test fail)
- No noticeable drivability symptoms in most cases — EVAP leaks generally don’t affect how the car runs
- A faint fuel odor near the rear of the vehicle in some cases, if the canister housing itself is cracked
- Code may be intermittent, appearing only after certain conditions (fuel level, ambient temperature) needed for the EVAP monitor to run
How to Diagnose P1457 on a Honda
- Check for P1456 alongside P1457. If both codes are present, start with the components shared by both tests (main EVAP hoses, fuel tank pressure sensor wiring) before narrowing down to canister-specific parts.
- Inspect the CVS valve and connector. Locate the canister vent shut valve (typically near the charcoal canister, often under the rear of the vehicle) and check the electrical connector for corrosion. Some scanners can command the valve open/closed for an active test.
- Visually inspect the charcoal canister. Look for cracks in the housing and check that all hose connections are seated and the seals aren’t hardened/cracked.
- Check the purge valve for leakage. With the engine off, the purge valve should be fully closed (no airflow through it). A valve that allows airflow when it should be sealed is a common P1457 cause.
- Smoke-test the canister-side hoses. A smoke machine connected to the EVAP system (via the purge line or a dedicated EVAP service port, depending on the model) will reveal leaks in canister-side hoses and seals that aren’t visible otherwise.
How to Fix P1457 on a Honda
| Component | Fix | Typical Cost |
|---|---|---|
| Canister vent shut (CVS) valve | Replace valve and/or repair connector | $60-$180 |
| Charcoal canister (cracked housing/seals) | Replace canister assembly | $100-$300 |
| Purge valve | Replace purge valve | $50-$150 |
| Purge line hose | Replace hose section | $15-$60 |
Confirming the Fix with an OBD2 Scanner
EVAP codes like P1457 can take a few drive cycles to clear permanently because the EVAP monitor only runs under specific fuel level and temperature conditions. The BlueDriver Bluetooth Pro can show you EVAP monitor status (complete/incomplete) so you know whether the test has actually run since your repair, rather than just checking if the Check Engine Light has come back on.
The Autel AL619 is also a solid budget option for clearing the code and checking monitor status after the repair.
If you have access to the THINKCAR ThinkDiag 2, its bidirectional controls can actuate the canister vent shut valve and purge valve directly on supported Honda models — letting you confirm both valves move and seal correctly without waiting for a full drive cycle.
Frequently Asked Questions
What’s the difference between P1456 and P1457?
Both are Honda EVAP leak codes detected during the same overall leak test, but they isolate different portions of the system. P1456 points to a leak on the fuel tank side (fuel cap, fuel tank pressure sensor, fuel tank itself), while P1457 points to a leak on the canister side (charcoal canister, CVS valve, purge valve, and their connecting hoses).
Can I have both P1456 and P1457 at the same time?
Yes. If both portions of the EVAP leak test fail, both codes can be stored together. In that case, it’s worth checking the components shared by both tests first — like the main EVAP canister hose routing — since a single issue there could affect both test segments.
Is P1457 dangerous to drive with?
No. P1457 is an emissions-related code and doesn’t affect drivability or engine performance. It will, however, cause a failed emissions/inspection test in jurisdictions that check for stored codes, so it’s worth fixing before your next inspection.
How long does it take for P1457 to clear after a repair?
The EVAP monitor needs specific conditions to run — typically a fuel level between roughly 15-85% and a cold-start followed by a drive of 20+ minutes. It can take 1-3 drive cycles after a repair for the monitor to complete and the code to clear permanently.
Can a loose gas cap cause P1457?
A loose or damaged gas cap is more commonly associated with P1456 (fuel tank side), since the cap is part of the fuel tank sealing system. However, on some Honda models the test segments overlap enough that a severe gas cap leak could potentially affect both test results — it’s still worth checking the cap and its seal as a quick first step regardless of which code you have.
Related Diagnostic Guides
- Honda P1456 Code Guide — the fuel-tank-side counterpart to this code
- Toyota P0455 Code Guide — how a similar large EVAP leak is diagnosed on Toyota’s system
- Honda Civic P0128 Code Guide — another common Civic-specific code
- 8 Best OBD2 Scanners for Honda Vehicles — scanner picks that show EVAP monitor status
