P0456 is an OBD-II code indicating a small leak in your vehicle's EVAP (evaporative emission control) system. The most common cause is a loose, cracked, or worn gas cap — a $5–$15 fix. P0456 will not clear itself while the leak exists; repair the cause and the code clears after two to three drive cycles, with or without a scan tool.
Symptoms of P0456
- Check engine light (MIL) on — steady, not flashing
- Failed emissions inspection
- No change in engine performance
What Causes a P0456 Code
- Loose, cracked, or worn gas cap ($5–$15) — most common.
- Cracked or disconnected EVAP hose ($5–$20)
- Failing purge valve ($15–$50)
- Failing vent valve ($20–$60)
- Charcoal canister damage ($50–$150) — cracking from road debris or saturation from repeated fuel overfilling
- Fuel filler neck corrosion ($50–$150) — more common on northern-climate vehicles with road salt exposure
How to Diagnose P0456
- Inspect and tighten the gas cap. Check the rubber O-ring for cracks or flattening. Tighten until the cap clicks.
- Clear the code and drive 2–3 complete drive cycles.
- Read all stored codes. [P0441] (incorrect purge flow) points to the purge valve. [P0446] (vent control circuit) points to the vent valve.
- Perform a smoke test. Smoke escaping from any hose, valve body, canister, or filler neck joint reveals the leak.
How to Fix P0456
- Replace the gas cap
- Replace the cracked EVAP hose
- Replace the purge valve
- Replace the vent valve
- Replace the charcoal canister
- Replace the fuel filler neck
How Much Does It Cost to Fix P0456?
| Repair | DIY Part Cost | Shop Cost (Parts + Labor) | Repair Time |
| Gas cap replacement | $5–$15 | $5–$15 (no labor needed) | 1 min |
| EVAP hose replacement | $5–$20 | $75–$200 | 30 min–1 hr |
| Purge valve replacement | $15–$50 | $100–$250 | 30 min–1 hr |
| Vent valve replacement | $20–$60 | $100–$250 | 30 min–1 hr |
| Charcoal canister replacement | $50–$150 | $200–$400 | 1–2 hrs |
Start with a new gas cap before paying for any other diagnosis.
Can You Drive With a P0456 Code?
Yes. A small EVAP leak does not affect engine performance, safety, or drivetrain function. Fix P0456 when practical so the check engine light remains available to flag other codes.
P0456 by Make
Jeep — Grand Cherokee (2011–2021) and Wrangler JK (2012–2018) are the highest-volume P0456 models. On the Grand Cherokee 3.6L Pentastar V6, the purge valve fails after 60,000–80,000 miles. On the Wrangler JK, start with the gas cap.
Ford — Escape (2013–2019) and F-150 (2015–2020) commonly trigger P0456. On EcoBoost-equipped Escapes (1.5L, 2.0L) — inspect all hose sections near the turbo and intercooler piping during a smoke test.
Toyota — Camry (2012–2020), RAV4 (2013–2019), and Corolla (2014–2019) trigger P0456 less frequently because Toyota's PCM more commonly stores [P0442] for small leaks.
Frequently Asked Questions
Q: Will code P0456 clear itself? P0456 will not clear itself while the leak exists. The PCM runs the EVAP monitor during specific driving conditions; if the leak is still present when the monitor runs, the code resets. Once the cause is repaired, P0456 clears on its own after two to three successful drive cycles. You can also clear it immediately with an OBD-II scanner after completing the repair.
Q: Will P0456 cause a failed emissions test? Yes. P0456 must be cleared and the EVAP monitor must complete and pass before the vehicle will pass a state emissions inspection. After repairing the cause and clearing the code, complete two to three full drive cycles before scheduling a retest. Retesting immediately after clearing the code will likely fail because the EVAP monitor will still show "not ready."