OBD-II Diagnostic Trouble Code
P2404 — EVAP Leak Detection Pump Sense Circuit Range/Performance
The ECM monitors a feedback (sense) signal from the EVAP leak detection pump, such as a pressure switch or current reading, to confirm the pump is running and building pressure or vacuum. This code means the sense signal did not match what the ECM expected while the pump was commanded. It applies to gasoline trucks with an EVAP leak detection pump.
Severity 2/5
Less common on commercial trucks
Service soon
Severity
Service soon
EVAP Leak Detection Pump Sense Circuit Range/Performance
Code
P2404
Category
Powertrain
Subsystem
Emissions
Truck-relevant
Less common
What this means for truckers
Service this week. Not an immediate stop, but ignoring it usually leads to a more expensive fix downstream.
Before you replace parts — try this first
P2404 on the Emissions system is most often faulty leak detection pump or its internal pressure switch giving an incorrect sense signal — not a dead part. On commercial diesels especially, work these in order before spending money on parts:
- Confirm the symptoms. Match what your truck is doing to the Symptoms section below. If the code is set but the symptoms are not there, clear the code and re-test after a drive cycle — it may not return.
- Clean and dry the sensor connector. Water, road salt, or oil seeping into a connector is the #1 fake sensor failure. Disconnect, look for green corrosion or moisture, spray with electrical contact cleaner, dry, reseat. Many faults clear here for $0.
- Inspect the wiring harness. Trace the wire from the sensor toward the ECM — look for chafing against the engine block, melted insulation near the turbo or exhaust, or pinch points where a clamp has rubbed through.
- Test the sensor before swapping it. Most Common Causes (below) list the expected voltage or resistance range — a $20 multimeter saves a $300 sensor swap that does not fix the problem.
- Only then, replace the part. Use the OEM or a tier-1 aftermarket. Cheap sensors throw the same code in two weeks.
Symptoms
Usually only the check-engine light comes on, with the EVAP monitor reporting incomplete. Some trucks also set EVAP leak codes. Drivability is normally fine, but the truck may fail an emissions or readiness check.
Common causes
- CommonFaulty leak detection pump or its internal pressure switch giving an incorrect sense signal ($200–$550)
- CommonCracked, disconnected or blocked hoses between the pump, canister and vent filter ($50–$250)
- OccasionalClogged pump filter or vent filter from road dirt ($40–$150)
- OccasionalHigh resistance or intermittent contact in the sense circuit wiring or connector ($80–$300)
How to fix
Inspect the pump, canister and vent hoses and the inlet filter for cracks, kinks, mud or insect nests
When to use: First check, especially on trucks that run on dirt or gravel roads
Watch the pump sense signal with a scan tool while commanding the pump on, and compare it to the expected switching or current pattern
When to use: To confirm whether the pump responds
Check sense circuit continuity and connector pin tension from the pump to the ECM
When to use: When the signal drops out or is erratic
Replace the leak detection pump assembly
When to use: When hoses and wiring are good and the pump does not produce a correct sense signal
Affects most
No specific vehicle pattern found in our complaint database. This code can appear on any vehicle that supports OBD-II diagnostics.
Related
- → Browse all DTC trouble codes
- → Decode a VIN to check codes for your truck
- → Owner-operator maintenance guides
- → P244A — Diesel Particulate Filter Differential Pressure Too Low
- → P244B — Diesel Particulate Filter Differential Pressure Too High
- → P244C — Exhaust Gas Temperature Too Low Bank 1
- → P244D — Exhaust Gas Temperature Too High Bank 1
- → P245A — EGR Cooler Bypass Control Circuit/Open
Frequently Asked Questions
Can I drive with code P2404?
P2404 is severity 2 — service this week. Not an immediate stop, but ignoring it usually compounds the problem. Most common cause for this code is a worn sensor or minor performance fault that won't strand you today but will get more expensive the longer you wait.
How much does it cost to fix P2404 on a commercial truck?
Total repair cost ranges $40–$550 depending on the root cause. The cheapest fix is usually the first one listed below — Faulty leak detection pump or its internal pressure switch giving an incorrect sense signal — which is also the most common. On commercial trucks the cost is usually higher than passenger vehicles due to part availability and shop labor rates ($120–185/hour at most truck shops, vs $90–130 at general auto shops). DIY-capable fixes (sensors, hoses, filters) are at the low end; major component replacements (turbo actuator, high-pressure fuel pump, transmission solenoid pack) are at the high end. Always diagnose with a scan tool BEFORE replacing parts — guessing wrong on a $1,500 turbo actuator when the actual issue was a $30 boost hose is a common expensive mistake.
Will P2404 fail a DOT inspection?
Yes — P2404 is an emissions-related code, and DOT inspectors check emissions compliance. An active emissions code with a check engine light can result in an out-of-service violation under FMCSA Part 393. The truck typically can't be moved until the code is cleared. Repeated emissions violations escalate to CSA scores.
What's the difference between P2404 and related codes?
P2404 is closely related to: P244A (Diesel Particulate Filter Differential Pressure Too Low), P244B (Diesel Particulate Filter Differential Pressure Too High), P244C (Exhaust Gas Temperature Too Low Bank 1), P244D (Exhaust Gas Temperature Too High Bank 1). These codes share the same subsystem (emissions) and often appear together. If you see this code, scan for the full code list — fixing the root cause usually clears multiple companion codes at once. If only P2404 is set without the companions, the issue is more isolated.
How do I prevent P2404 from coming back after a repair?
For P2404 (EVAP Leak Detection Pump Sense Circuit Range/Performance), prevention centers on the emissions system. Keep up with PM on the EGR system — clean the valve at 200K miles. Use OEM-spec air filters. Don't ignore minor codes; they often escalate into bigger emissions failures.