Toyota P2401 Code: EVAP Leak Detection Pump Stuck OFF
In Toyota's key-off EVAP test, the canister module's leak detection pump didn't pull the expected vacuum.
At a glance
Severity: Low
- Meaning
- EVAP Leak Detection Pump Stuck OFF
- System
- Emission Controls · Powertrain
- Safe to drive?
- Yes, short term
- Typical repair cost
- $60–$1,100
- DIY difficulty
- Moderate
Many Toyota and Lexus models from roughly the mid-2000s on check the EVAP system for leaks while parked, using a canister pump module bolted to the charcoal canister. The module contains a small electric leak detection pump, a vent valve, a pressure sensor and a 0.02-inch reference orifice. About five hours after the ignition is switched off (later if the engine was still hot), the ECM wakes up and first runs the pump against that orifice to learn a reference vacuum. If the reading stays weaker than about -1.06 kPa (roughly -4 inches of water) or goes deeper than about -4.85 kPa, the ECM decides the pump isn't working and, after two such tests, stores P2401 and lights the check engine light. So on a Toyota P2401 is a pressure-based result, not only the generic circuit-low meaning, and the air inlet hose and filter matter as much as the pump.
Can I keep driving? There's no effect on how the car drives, and it's safe to use normally. It will fail an emissions test, and until it's fixed real EVAP leaks can't be detected.
How to read P2401
- P Powertrain
- 2 Generic (SAE)
- 4 Auxiliary emission controls
- 01 Specific fault
Symptoms
- Check engine light on with no change in how the engine runs
- EVAP readiness monitor stays incomplete
- No faint humming from under the rear of the car hours after parking, where it used to be heard
- Often stored together with P2402, P2419 or reference-pressure codes
- Occasionally a fuel vapor smell if the canister has been flooded
Possible causes
Ranked by how often each cause is behind this code (editorial estimate).
- Leak detection pump in the canister pump module failed, often after water got into the module
- Air inlet line or canister filter blocked by mud, debris or insect nests, or the hose disconnected
- Corroded or loose connector, or damaged harness to the module under the car
- Vent valve or pressure sensor inside the module faulty
- Reference orifice clogged with dirt or carbon dust
- ECM fault
Diagnosis step by step
Confirm the system and related codes
Look under the car near the fuel tank for the charcoal canister with the pump module attached. Note any P2402, P2419 or P043E/P043F codes, because a shared module or air inlet problem often sets several of them at once.
Tools: Flashlight, OBD-II scanner
Inspect the module and connector
Check the pump module and its connector for mud, water, green corrosion or a cracked housing. A module that has been sitting in water usually needs replacing, and on many models it is only sold together with the canister.
Tools: Flashlight
Check the air inlet path
Follow the fresh-air hose from the module to its inlet, often up near the filler neck, and the small canister filter in that line. Disconnect it and confirm air flows freely; a blocked inlet makes the reference test fail even with a good pump.
Tools: Pliers, Flashlight
Run the pump with a scan tool
With a Toyota-capable scan tool, run the EVAP system check or activate the leak detection pump while watching EVAP pressure. With the vent open to the orifice, pressure should drop smoothly to a steady negative value between about -1 and -5 kPa; no change at all means the pump isn't running or isn't moving air.
Tools: OBD-II scanner
Check power and ground at the module
If the pump doesn't run during the test, back-probe the pump motor pins while it is commanded on and confirm about 12 V and a solid ground. Voltage present but no pump operation condemns the module; missing voltage points to wiring or the ECM.
Tools: Multimeter
Repair and let the monitor run
After replacing the module, canister or inlet parts, clear the code and park the car overnight with the fuel tank between roughly a quarter and three-quarters full. The key-off monitor runs by itself hours later; confirm the EVAP monitor shows complete before any test.
Tools: OBD-II scanner
Where the parts are
- 1Gas cap
- 2Charcoal canister
- 3Purge valve
- 4Vent valve
- 5Fuel pump
- 6Intake manifold
Repair options & costs
| Repair | DIY? | Estimated cost |
|---|---|---|
| Clear or replace blocked air inlet hose / canister filter | Yes | $60–$200 |
| Repair canister pump module connector or harness | No | $100–$300 |
| Replace canister pump module | Yes | $250–$550 |
| Replace charcoal canister assembly with integrated pump module | No | $500–$1,100 |
Rough US estimates for parts and labor; shop rates vary by region. Not a quote.
Emissions / smog test impact
Will fail
P2401 lights the check engine light and leaves the EVAP monitor incomplete, so the vehicle fails an OBD smog check. Many states allow one incomplete monitor on newer model years, but not an active check engine light.
Frequently asked questions
Is Toyota's P2401 the same as the generic P2401?
The number is the same, but Toyota uses it for a pump that fails to produce the expected reference vacuum during the key-off test. That can be the pump, the module wiring or a blocked air inlet, not only a low-voltage circuit.
Why would my car make noise under the rear hours after I parked?
That's the canister pump module running the key-off leak test, which is normal. Toyota's ECM wakes up about five hours after shutdown and runs the pump for several minutes.
Do I have to replace the whole charcoal canister?
On many Toyota models the pump module is sold only as part of the canister assembly, so yes. On others it is available separately; check the parts catalog for your VIN before ordering.
Will P2401 affect fuel economy or performance?
No. It only disables the EVAP leak test. The concern is that a real leak in the fuel vapor system would go undetected, and the car won't pass an emissions test.
Sources
- Manufacturer public service information (cross-checked)
- US EPA – On-Board Diagnostics (OBD) program
- Methodology: How We Build Code Pages · Data Sources We Use · Editorial Policy