P0440 on Mazda vehicles
EVAP System Malfunction (Generic) — what it means on a Mazda, whether it's safe to drive, and the fixes by model and year.
P0440 on a Mazda means evap system malfunction (generic). Most vehicles stay drivable short-term, but diagnose it promptly. The most common cause is loose, worn, or wrong-spec fuel cap (typically $15–$60). Pick your Mazda model below for its known failure patterns, recalls, and TSBs.
What does P0440 mean on a Mazda?
P0440 is a generic evaporative emission (EVAP) system fault. The EVAP system captures fuel vapors from the tank and routes them through the charcoal canister to be burned by the engine instead of vented into the atmosphere. P0440 is set when the ECM detects that this sealed system has lost its ability to hold pressure or vacuum during a leak test. It is almost always the first sign of a small leak somewhere between the fuel tank and the engine intake.
P0440 is a standardized OBD-II code, so its definition is the same on every Mazda. What differs by model and engine is which cause is most likely — pick your Mazda model below for a diagnosis tuned to its known failure patterns, recalls, and TSBs.
Is it safe to drive a Mazda with P0440?
In most cases a Mazda stays drivable for short trips with P0440 active, but diagnose and repair it promptly. This is a low-severity code — ignoring it can lead to further damage or a failed emissions test. Exact tolerance depends on the model and engine.
What causes P0440 on a Mazda?
| Cause | Likelihood | Estimated repair (USD) |
|---|---|---|
| Loose, worn, or wrong-spec fuel cap — Always the first thing to check — costs nothing to tighten or replace. | Most common | $15–$60 |
| Cracked, kinked, or disconnected EVAP hose | Common | $30–$200 |
| Failed EVAP purge valve (purge solenoid) stuck open or closed | Common | $80–$300 |
| Failed EVAP canister vent valve / vent solenoid | Common | $80–$350 |
| Cracked or damaged EVAP charcoal canister | Occasional | $200–$600 |
| Pinhole leak in fuel filler neck or tank seam | Occasional | $150–$800 |
| Failed fuel tank pressure sensor | Occasional | $100–$350 |
Repair costs are typical US ranges and vary by Mazda model, model year, and labor rate. A diagnostic trouble code is a symptom, not a guaranteed failed part — confirm the root cause before replacing anything.
P0440 by Mazda model
Select your Mazda model and year for a P0440 diagnosis tuned to that vehicle's failure patterns, recalls, and TSBs.
Mazda CX-5
205 NHTSA owner complaints · 1 recalls on record across the years covered below.
Complaint and recall counts are NHTSA totals for the model years covered on this site, not counts specific to P0440.
P0440 on other makes
Other codes on Mazda vehicles
P0440 on a Mazda: frequently asked questions
What does diagnostic trouble code P0440 mean on a Mazda?
P0440 is a generic evaporative emission (EVAP) system fault. The EVAP system captures fuel vapors from the tank and routes them through the charcoal canister to be burned by the engine instead of vented into the atmosphere. P0440 is set when the ECM detects that this sealed system has lost its ability to hold pressure or vacuum during a leak test. It is almost always the first sign of a small leak somewhere between the fuel tank and the engine intake. P0440 is a standardized OBD-II code, so the definition is the same on every Mazda — which cause is most likely varies by model and engine.
What are the symptoms of P0440 on a Mazda?
Check Engine Light is illuminated. Faint fuel smell when filling the tank or shortly after. No drivability problem in most cases. Fuel-cap warning light on some vehicles. Vehicle will fail emissions / smog testing
What causes P0440 on a Mazda?
Loose, worn, or wrong-spec fuel cap (most-common). Cracked, kinked, or disconnected EVAP hose (common). Failed EVAP purge valve (purge solenoid) stuck open or closed (common). Failed EVAP canister vent valve / vent solenoid (common). Cracked or damaged EVAP charcoal canister (occasional). Pinhole leak in fuel filler neck or tank seam (occasional). Failed fuel tank pressure sensor (occasional)
Is it safe to drive a Mazda with P0440?
In most cases a Mazda stays drivable for short trips with P0440 active, but it should be diagnosed and repaired promptly — this is a low-severity code. Ignoring it can lead to further damage or a failed emissions test. Exact tolerance depends on the model and engine.