P2403

EVAP System Leak Detection Pump Sense Circuit/Open

Q: Is it safe to drive with P2403?

Yes. It's an emissions-system circuit fault with no effect on power or safety, but it should be repaired so the car passes emissions.

Q: Can I just clear P2403?

It returns when the EVAP monitor next runs unless the open circuit or pump is repaired.

EVAP / emissions Generic OBD-II Low

What it means

P2403 refers to the evaporative emissions (EVAP) leak-detection pump's sense circuit reading open. That pump pressurizes the EVAP system to check for fuel-vapor leaks; when its sense (feedback) circuit is open, the PCM can't run the leak test. This is an emissions-monitor circuit fault — the engine runs and drives normally, but the vehicle won't pass an emissions test until it's repaired.

Low

Can I keep driving? Yes — the car drives normally. This is an EVAP monitor circuit fault with no effect on power; it mainly prevents the leak test and will fail emissions until fixed.

Real-world scan data

Seen in

scans in the past year

Found in

<0.1%

of scans

<0.1%

of scans that found faults

Figures reflect only diagnostic scans recorded through our own apps and tools. Cars are typically scanned because a symptom or warning light prompted it, so these counts describe our scan records — not the incidence of faults in any model, and not the quality, reliability, or safety of any vehicle. No comparison between manufacturers or models is implied. All trademarks belong to their respective owners; no affiliation or endorsement is implied.

Common symptoms

What you'll notice

Check-engine light on — usually the only symptom
May fail an emissions or smog test
No noticeable change in how the vehicle runs
A faint fuel odor only if an actual EVAP leak is also present

Common causes

Most likely first

Open or damaged wiring/connector at the EVAP leak-detection pumpLikely
Faulty leak-detection pumpCommon
Corroded pump connector terminalsCommon
Blown fuse feeding the leak-detection pump circuitLess often
Faulty PCM (rare)Less often

How to diagnose & fix

Work through it in order

Inspect the leak-detection pump connector and wiring for opens, corrosion, or damage.
Check the fuse and power feed to the pump circuit.
Test the pump and its sense circuit against the manufacturer's spec.
Replace the leak-detection pump if its sense circuit is internally open.
Clear the code and confirm the EVAP monitor completes.

FAQ

Quick answers

Is it safe to drive with P2403?+

Yes. It's an emissions-system circuit fault with no effect on power or safety, but it should be repaired so the car passes emissions.

Can I just clear P2403?+

It returns when the EVAP monitor next runs unless the open circuit or pump is repaired.

Read & clear P2403 yourself

Scan your car, confirm the code, and clear it once it's fixed — with OBD DashX on your phone.

▶ Get it on Google Play

✓ Verified name — SAE J2012 / ISO 15031-6Guidance reviewed by OBD DashX