OBD-II Diagnostic Trouble Code
P1455 — EVAP System Leak (Gross Leak)
P1455 is a manufacturer-specific code on gasoline trucks that commonly means the ECM detected a large (gross) leak or no flow in the EVAP system during self-test. The tank and lines could not hold the expected vacuum. Meaning can vary by OEM.
Severity 2/5
Less common on commercial trucks
Service soon
Severity
Service soon
EVAP System Leak (Gross Leak)
Code
P1455
Category
Powertrain
Subsystem
Emissions
Truck-relevant
Less common
What this means for truckers
P1455 (EVAP System Gross Leak) — gas engine.
Before you replace parts — try this first
P1455 on the Emissions system is most often loose, missing or damaged fuel cap — 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
Check-engine light and possibly a fuel smell. Drivability is normally unaffected.
Common causes
- CommonLoose, missing or damaged fuel cap ($15–$60)
- CommonCracked or disconnected EVAP hose ($80–$350)
- OccasionalFaulty purge or vent valve ($100–$400)
- OccasionalLeaking charcoal canister ($200–$700)
- RareLeaking fuel filler neck or tank seal ($250–$900)
How to fix
Check and replace the fuel cap
When to use: First step
Smoke test the EVAP system
When to use: When the cap is good
Test the purge and vent valves
When to use: When no leak is visible
Repair the leaking hose, canister or filler neck
When to use: When the leak is found
Affects most
No specific vehicle pattern found in our complaint database. This code can appear on any vehicle that supports OBD-II diagnostics.
Related
Frequently Asked Questions
Can I drive with code P1455?
P1455 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 P1455 on a commercial truck?
Total repair cost ranges $15–$900 depending on the root cause. The cheapest fix is usually the first one listed below — Loose, missing or damaged fuel cap — 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 P1455 fail a DOT inspection?
Yes — P1455 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 P1455 and related codes?
P1455 is closely related to: P1404 (EGR Closed Position Performance), P1410 (EVAP System Pressure Sensor), P1450 (Unable to Bleed Up Fuel Pressure). 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 P1455 is set without the companions, the issue is more isolated.
How do I prevent P1455 from coming back after a repair?
For P1455 (EVAP System Leak (Gross Leak)), 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.