P2402 Code: EVAP Leak Detection Pump Control Circuit High
The leak pump's control line reads too high – usually a short to a 12-volt wire or an overloaded driver.
At a glance
Severity: Low
- Meaning
- EVAP Leak Detection Pump Control Circuit High
- System
- Emission Controls · Powertrain
- Safe to drive?
- Yes, short term
- Typical repair cost
- $20–$1,300
- DIY difficulty
- Moderate
When the engine computer switches the leak detection pump on, it expects the voltage on the control line to change in a predictable way and the current to stay within a limit. P2402 sets when that line stays high – for example because the wire has rubbed against a circuit that carries battery voltage, or because the pump winding draws so much current that the computer's protected driver shuts itself off. Either way, the pump or its solenoid can't be switched and the EVAP leak test doesn't run. The code shows up on vehicles with the vacuum-type LDP (older Chrysler, Dodge, Jeep, US-market VW) as well as on electric canister pump modules used by Toyota, Lexus and several European brands.
Can I keep driving? The car is safe to drive and the engine runs normally. A wire that's shorted to another powered circuit can affect that circuit too, so if lights or a trailer connector act up at the same time, have it looked at soon.
How to read P2402
- P Powertrain
- 2 Generic (SAE)
- 4 Auxiliary emission controls
- 02 Specific fault
Symptoms
- Check engine light, driveability normal
- Leak detection pump stays silent during a scan tool output test
- Code appears only with the headlights, tail lights or a trailer connected
- Tail light, trailer or other rear-harness circuits behaving oddly at the same time
- EVAP monitor never completes
Possible causes
Ranked by how often each cause is behind this code (editorial estimate).
- Control wire shorted to a 12-volt circuit in the rear harness, such as tail light or fuel pump feed
- Poor aftermarket splice – trailer wiring, remote starter or alarm tapped into the wrong wire
- Pump winding shorted so it draws excess current and trips the computer's driver protection
- Incorrect or non-matching replacement pump with the wrong coil resistance
- Corroded connector letting the supply pin leak onto the control pin
- Faulty driver inside the engine computer
Diagnosis step by step
Note when the code sets
Look at the freeze frame data and try to reproduce the fault. If P2402 returns only with the lights on or a trailer plugged in, the control wire is almost certainly touching a lighting circuit.
Tools: OBD-II scanner
Look for aftermarket wiring
Follow the harness from the canister toward the rear lights and the hitch. Scotch-lock taps, twisted splices or a trailer module wired near the tank are common places for a control wire to pick up voltage.
Tools: Flashlight
Check the control wire for stray voltage
Disconnect the pump and the engine computer connector, then turn the key on and switch on the lights. Measure between the control wire and ground: it should read 0 V. Anything close to battery voltage proves a short to power.
Tools: Multimeter
Measure pump current or resistance
Measure the pump's resistance and compare it with the specification. A winding that reads far too low draws enough current to trip the driver; if you have an amp clamp, current well above the specified value when the pump is powered confirms it.
Tools: Multimeter
Command the pump after the repair
Once the short or the pump is fixed, use the scan tool output test to switch the pump on and off. You should hear it respond each time and the code should not return with the lights on.
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 |
|---|---|---|
| Remove faulty aftermarket splice and repair wiring properly | No | $80–$250 |
| Repair control wire shorted to a power circuit | No | $120–$350 |
| Clean and seal pump connector | Yes | $20–$100 |
| Replace leak detection pump or canister pump module | No | $170–$650 |
| Replace or repair engine computer | No | $500–$1,300 |
Rough US estimates for parts and labor; shop rates vary by region. Not a quote.
Notes by brand
Field data
| Toyota | 8 | Corolla, Scion Xa, Yaris Liftback |
|---|
Source: NHTSA Complaints API (US government open data), analyzed by DTC mention.
Emissions / smog test impact
Will fail
With the check engine light on, P2402 fails an OBD-based emissions inspection, and the EVAP monitor stays incomplete. Repair first, then drive for a few days before retesting.
Frequently asked questions
Why would my trailer wiring cause an EVAP code?
Trailer and tail light wires run along the same rear harness as the pump's control wire. A careless splice or a pinched loom can feed lighting voltage into the pump circuit, and the engine computer reads that as 'circuit high'.
Does 'circuit high' mean the pump is running all the time?
Not necessarily. More often the pump can't be switched at all, because the computer's driver shuts down when it sees the wrong voltage or too much current. A scan tool output test shows whether it responds.
Will a cheap replacement pump fix it?
Only if its electrical values match the original. A pump with a lower coil resistance can draw too much current and set P2402 again even though it's brand new.
Can P2402 and P2401 show up together?
Yes, especially with a corroded connector or an intermittent harness fault that sometimes grounds and sometimes touches power. In that case the connector and harness are more likely than the pump.