P043F: How to Diagnose & Fix — Evaporative Emission System Leak Detection Reference Orifice High Flow
2 vehicles · 1 makes · $150-$500 repair
How to diagnose and fix P043F: most-reported vehicles
Ranked by owner reports. Each card gives the symptoms, how to confirm the cause, the fix, parts and sources for that vehicle.
Toyota RAV4 · 2006–2010
Toyota T-SB-0046-10 applies to specified 2006-2010 RAV4 production and addresses liquid fuel entering the EVAP system. The documented gates are an illuminated MIL with DTC P043E, P043F, P2401, P2402 and/or P2419, or an intermittent warm rough idle reproduced while commanding the purge VSV, followed by physical confirmation of fuel in the applicable EVAP vent hoses. It is not a general 2001-2012 charcoal-canister failure card and does not support the old P0440/P0441/P0442/P0446/P0455 mapping.
Common Symptoms
- MIL with one or more supported EVAP DTCs
- Intermittent rough idle at operating temperature during the bulletin's purge-VSV test
- Liquid fuel physically confirmed in a specified EVAP vent hose
How to Fix
Follow T-SB-0046-10's sequence: check for the supported DTCs; if none are stored, active-test the purge VSV at warm idle; then disconnect and inspect the specified tank-to-canister and canister-to-key-off-pump hoses for liquid fuel. If the gates are not met, the bulletin does not apply and normal EVAP diagnosis continues. If fuel is confirmed, the required tank, canister and possibly canister-filter/protector scope depends on which hose contains fuel. Do not replace a gas cap, vent valve or full canister from a generic code list. The former federal and California emissions-warranty windows are expired; obtain a diagnosis and estimate first.
Owner tips & cautions
- TipSave freeze-frame data and all EVAP codes before clearing them; the bulletin requires exact code/test and liquid-fuel confirmation gates.
- WarningDo not guess at an EVAP canister, gas cap or vent valve from a generic code; T-SB-0046-10's component scope changes based on where liquid fuel is found.
Sources for this issue (1)
Toyota Sienna · 2011–2020
Third-generation Siennas commonly throw EVAP (evaporative emissions) faults as the system ages. Failure points include the canister vent solenoid/VSV sticking, the leak-detection pump and reference orifice, the purge valve, and a worn or loose gas cap. Beyond the check engine light and an emissions/smog failure, a stuck-closed vent can make the tank hard to refuel (pump clicks off repeatedly), while a stuck-open vent or cracked line can produce a fuel-vapor smell.
Common Symptoms
- Check engine light with EVAP codes
- Fails state emissions/smog test
- Gas pump clicks off repeatedly / difficult to refuel
- Faint fuel-vapor smell near the vehicle
- No drivability change but persistent CEL
How to Fix
Check the gas cap first, then smoke-test the EVAP system to find leaks. Codes guide the fix: P043E/P043F point to a clogged or ruptured reference orifice, P2401/P2402/P2419 to the leak-detection pump/switching valve, and P0441/P0446/P0455 to purge/vent flow or large leaks. Typical repairs (vent solenoid, purge VSV, leak-detection pump, or hoses) run roughly $150-$500 including diagnosis.
What you need to fix it
Only diagnosis- and fitment-reviewed repair parts are linked here.
- Toyota 77300-06040 fuel tank cap assembly
replace a cap that fails seal, tether or ratchet inspection on the matching early branch Fitment/availability: Early fuel-cap branch cataloged for Sienna through the relevant early third-generation production; confirm VIN and production …
- Toyota 77300-07030 fuel tank cap assembly
replace a cap that fails inspection on the matching middle production branch Fitment/availability: Middle fuel-cap branch cataloged for 2013-2017 Sienna with production-date overlap; confirm VIN against the catalog before ordering Fitmen…
- Toyota 77300-07040 fuel tank cap assembly
replace a cap that fails inspection on the matching late production branch Fitment/availability: Late fuel-cap branch used from the applicable 2016/2017 production change through 2020; confirm VIN and build date Fitment/availability: Shi…
- Toyota 77740-08070 charcoal canister assembly
replace the early canister only after smoke/active testing confirms its internal pump, orifice, vent or canister failure Fitment/availability: Canister branch cataloged for 2011-2016 Sienna and some 2017 applications; confirm VIN, drivet…
- Toyota 77740-08090 charcoal canister assembly
replace the late canister only after smoke/active testing confirms its internal pump, orifice, vent or canister failure Fitment/availability: Canister branch cataloged for 2017-2020 Sienna 3.5L; confirm VIN and production because 2017 ov…
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Sources for this issue (3)
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P043F code reference
General diagnostic-code context. The code alone does not confirm a cause for your vehicle; use the applicable issue card and its sources.
Frequently asked questions
What does P043F mean?
P043F stands for "Evaporative Emission System Leak Detection Reference Orifice High Flow." Generic OBD-II code. The engine control module runs a calibration check through a small precision reference orifice (roughly 0.02 in) in the EVAP leak detection pump/module, and measured flow through that orifice was higher than the expected specification. Because the orifice is the yardstick the module uses to size real leaks, a high-flow reading means the EVAP leak test can no longer be trusted. The driver usually notices nothing beyond a check engine light, but the vehicle will fail an emissions test. It frequently sets alongside P043E, P2401, P2402 or P2419, which point at the same leak detection pump module on the charcoal canister.
What are the most common causes of P043F?
The most common causes of P043F are: Damaged, enlarged, or cracked reference orifice inside the EVAP leak detection pump/module, Leak in the hose or line between the leak detection module and the canister or fuel tank, Failed EVAP leak detection pump assembly, Loose, missing, or non-sealing fuel cap / filler neck seal allowing extra flow, Electrical fault in the leak detection pump circuit skewing the measurement, Rarely, a PCM/ECM software calibration or module fault. The specific cause varies by vehicle.
How much does it cost to fix P043F?
Repair costs for P043F range from $150 to $500, depending on the vehicle and root cause.
Which vehicles are affected by P043F?
Au7o has documented P043F across 2 vehicle models from 1 manufacturers: Toyota.
Content compiled with AI assistance using NHTSA complaints, TSBs, and owner reports. May contain errors. Always verify with your vehicle's service manual.