OBD-II Diagnostic Trouble Code
P2402 — EVAP Leak Detection Pump Control Circuit High
The ECM detected a voltage on the EVAP leak detection pump control circuit that is higher than expected for the commanded state. This usually indicates a short to voltage on the control wire or an internal fault in the pump, so the ECM cannot properly run the EVAP leak test. This code applies to gasoline trucks with an EVAP system; diesel trucks do not use a leak detection pump.
Severity 2/5
Less common on commercial trucks
Service soon
Severity
Service soon
EVAP Leak Detection Pump Control Circuit High
Code
P2402
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
P2402 on the Emissions system is most often control wire to the leak detection pump chafed and shorted to a battery or ignition feed — 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
On a gas medium-duty truck the check-engine light is usually the only symptom. The EVAP leak self-test will not complete, so readiness monitors stay incomplete and the truck may fail an emissions inspection. Drivability is normally unaffected, though some trucks set additional EVAP codes alongside it.
Common causes
- CommonControl wire to the leak detection pump chafed and shorted to a battery or ignition feed ($100–$350)
- CommonFailed leak detection pump with an internally shorted solenoid or motor ($200–$550)
- OccasionalCorroded or water-intruded pump connector near the fuel tank or canister ($60–$200)
- RareECM driver fault ($800–$2000)
How to fix
Inspect the pump harness along the frame rail for rubbing on brackets, and look for melted or pinched insulation
When to use: First step, especially if the harness runs near the exhaust or crossmembers
Unplug the pump and check the control wire for voltage with the key on; if voltage is still present, trace the short in the harness
When to use: When the code returns right after clearing
Measure pump coil resistance against spec and command the pump with a scan tool; replace the pump if it is out of range or does not respond
When to use: When the wiring tests good
Clear the code and run the EVAP monitor drive cycle to confirm the repair
When to use: After any repair, before an emissions inspection
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 P2402?
P2402 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 P2402 on a commercial truck?
Total repair cost ranges $60–$2000 depending on the root cause. The cheapest fix is usually the first one listed below — Control wire to the leak detection pump chafed and shorted to a battery or ignition feed — 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 P2402 fail a DOT inspection?
Yes — P2402 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 P2402 and related codes?
P2402 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 P2402 is set without the companions, the issue is more isolated.
How do I prevent P2402 from coming back after a repair?
For P2402 (EVAP Leak Detection Pump Control Circuit High), 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.