P0440 Code: Toyota Tacoma (2016-2023) - Causes, Symptoms & Fixes

No NHTSA complaints found for this make/model/year/issue combination. No recalls found in NHTSA database.

Note on data limitations: The provided data indicates no NHTSA complaints and no recalls for the 2016-2023 Toyota Tacoma related to P0440. This guide combines those limitations with general, vehicle-specific EVAP system knowledge to help diagnose P0440 on these Tacomas. The exact cause can vary by vehicle and region, and some repairs may require professional equipment (smoke testing, scan tools, access to OEM specs).

1. CODE MEANING AND SEVERITY

• Code meaning: P0440 = Evaporative Emission Control System Malfunction. The engine computer (ECU/PCM) detected an issue in the EVAP system that could allow fuel vapors to escape to the atmosphere.
• Likely symptoms: Check Engine Light (MIL) on; EVAP-related readiness monitor may not complete; possible fuel odor; potential minor impact on fuel economy. Driveability is usually unaffected.
• Severity for a 2016-2023 Toyota Tacoma: Moderate. It can cause a failed emissions test in some regions and may eventually lead to more costly EVAP system issues if leaks worsen. In many cases, a simple fix (gas cap, minor hose repair, or EVAP valve replacement) resolves the code.

2. COMMON CAUSES ON TOYOTA TACOMA

• Loose or damaged gas cap or poor seal.
• Faulty purge valve (solenoid) stuck open or closed or electrical fault in its circuit.
• Faulty vent valve or vent valve circuit (if equipped separately).
• Cracked or degraded EVAP hoses, clamps, or fittings (especially near the purge/vent components or canister).
• Leaking or saturated charcoal canister (canister canister damage or contamination).
• Leaks around the fuel filler neck, neck gasket, or related plumbing.
• Leak Detection Pump (LDP) failure or its wiring (varies by model year and market; some Tacomas use an LDP in the EVAP system).
• Wiring harness or PCM/ECU communication issues affecting EVAP control.
• In rare cases, software/ECU calibration or monitor fault causing the EVAP readiness test to fail.

3. SYMPTOMS

• Check Engine Light (MIL) on or steadily illuminated.
• Gas cap warning message or repeated “gas cap” reassurance on the dash (even if the cap is fine).
• Noticeable fuel odor around the vehicle, especially after fueling.
• Slight decrease in fuel economy (more noticeable if a large EVAP leak exists).
• In some cases, no noticeable drivability issue; the vehicle runs normally.

4. DIAGNOSTIC STEPS
   Note: Start with the simplest checks and progressively move to more involved tests. Document findings at each step.

• Step 1: Confirm DTC and readiness

  • Retrieve DTCs with a scan tool. Confirm the active P0440 code and note any related codes (P0441, P0442, P0446, P0455, P0456, etc.).
  • Check the EVAP readiness monitors and whether they are “not ready” or “ready.” A non-ready EVAP monitor can indicate an intermittent fault.

• Step 2: Visual inspection (start with gas cap)

  • Inspect the gas cap for cracks, a missing/damaged seal, or improper threading. Replace with a high-quality/specified gas cap and ensure it is tightened properly (usually finger-tight plus a final snug turn; avoid overtightening).
  • Inspect the filler neck and exterior area for damage or cracks.
  • Inspect visible EVAP hoses and vacuum lines for cracks, stiffness, swelling, or disconnection. Look for cracked pots, brittle hoses, or loose clamps.
  • Inspect the charcoal canister if accessible for cracks or contamination.

• Step 3: Inspect purge and vent valves

  • Locate the EVAP purge valve (solenoid) and vent valve (if separate). Check for secure electrical connectors and damaged wiring.
  • Use a multimeter to verify resistance in the purge valve according to OEM spec; check that the valve is not stuck and has proper coil resistance.
  • With the ignition on (engine off), listen for valve operation when commanded from a scan tool, if possible. Some Tacomas require professional testing equipment to command and hear/see valve response.

• Step 4: Check for leaks and perform a leak test

  • If no obvious issue from Step 2 and 3, perform a smoke test of the EVAP system. This requires specialized equipment (smoke machine) and is typically done by a shop.
  • If a smoke test isn’t available, consider a controlled pressure test of the EVAP system with a diagnostic pump to identify a leak point, though this is more advanced and equipment-intensive.

• Step 5: Inspect the canister and lines

  • Ensure the charcoal canister is not physically damaged or saturated with fuel vapors. Look for signs of contamination or odor.
  • Inspect all EVAP lines for kinks, cracking, or disconnections near the canister, purge valve, vent valve, and anywhere they route under the hood and to the intake manifold.

• Step 6: Check PCM/ECU and software considerations

  • In rare cases, software calibration or a voltage/fault in the ECU can trigger P0440. If no hardware fault is found, a dealership-level reflash or software update may be warranted.

• Step 7: Clear codes and re-test

  • After performing repairs, clear codes and drive normally for a few days. Recheck to ensure the P0440 code returns or if the EVAP monitor completes (passes) during drive cycles.

• Step 8: If the code persists

  • If no leakage is found after steps 1–6, re-evaluate component connections, consider replacing suspect components (start with less expensive parts such as gas cap, purge valve, or vent valve), and re-test. If still unresolved, diagnostic testing or replacement of the EVAP canister or LDP may be necessary.

5. RELATED CODES

• P0441: Evaporative Emission Control System Incorrect Purgeflow
• P0442: Evaporative Emission Control System Leak Detected (small leak)
• P0446: Evaporative Emission Control System Purge Control Valve Circuit
• P0455: Evaporative Emission Control System Large Leak Detected
• P0456: Evaporative Emission Control System Very Small Leak Detected
• Other P044x codes can indicate EVAP leak or purge issues; diagnosis often follows the same path (gas cap, purge valve, hoses, canister, and leak testing).

6. REPAIR OPTIONS AND COSTS (2025 PRICES)
   Disclaimer: Actual costs vary by region, shop, and vehicle condition. The ranges below reflect typical shop charges and parts pricing in 2025 for a 2016-2023 Toyota Tacoma.

• Gas cap replacement

  • Parts: $15–$50
  • Labor: often not required if you do it yourself; if installed by a shop, 0–0.5 hour
  • Typical total: $15–$80

• Gas cap reseal/re-torque and cleaning of filler area

  • Parts: minimal
  • Labor: 0.25–0.75 hour
  • Typical total: $20–$120

• EVAP purge valve (solenoid) replacement

  • Parts: $50–$150
  • Labor: 1–2 hours
  • Typical total: $150–$350

• EVAP vent valve replacement (if separate)

  • Parts: $50–$150
  • Labor: 1–2 hours
  • Typical total: $150–$350

• Charcoal canister replacement (evap canister)

  • Parts: $250–$450
  • Labor: 1.5–3 hours
  • Typical total: $500–$1,100

• Leak Detection Pump (LDP) replacement (if equipped and needed)

  • Parts: $120–$250
  • Labor: 1–2 hours
  • Typical total: $250–$600

• EVAP system diagnostic/testing

  • Diagnostic fee or shop time: $80–$150 (often applied toward repair if a repair is performed)

• EVAP hose/line repair (cracked or disconnected hoses)

  • Parts: $5–$50 per hose
  • Labor: 0.5–1 hour
  • Typical total: $60–$300 depending on number of lines replaced

• Miscellaneous/combination repairs

  • If multiple issues exist (gas cap, purge valve, hose, and a small leak), total repair cost may be toward the upper end of the ranges above (roughly $200–$1,000+ depending on parts replaced and labor rates).

7. DIY VS PROFESSIONAL

• DIY-friendly tasks (if you have basic tools and mechanical comfort):

  • Replacing a faulty gas cap.
  • Inspecting and replacing easy-to-access hoses; reseating clamps.
  • Visual inspection of purge/vent valves; replacing simple hoses or clamps.
  • Clearing codes after replacement and test-drive to see if the EVAP monitor completes.

• Tasks typically best left to professionals:

  • Smoke testing to locate EVAP leaks.
  • Diagnosing a persistent P0440 when no obvious external leak is found.
  • Replacing the charcoal canister or LDP.
  • Electrical testing of purge/vent valve circuits and ECU-related issues.
  • Any work that involves the EVAP canister or the fuel system components beyond simple hose replacements.

• Tools you may need if you DIY:

  • OBD-II scanner to read/clear codes and monitor EVAP readiness.
  • Basic hand tools and clamps for hoses.
  • Smoke machine or smoke tester (for locating leaks).
  • Multimeter for valve resistance checks (if you choose to test purge/vent valve circuits).
  • Service manual or OEM wiring diagrams for Toyota Tacoma 2016–2023 to verify correct specs and connector pinouts.

8. PREVENTION

• Use a high-quality, properly rated gas cap and ensure you always tighten it securely after fueling.
• Fuel regularly to prevent moisture buildup; avoid letting the fuel level stay extremely low, which can draw air into the EVAP system.
• Inspect the EVAP system connections and hoses during routine maintenance (every 30,000–60,000 miles or per Toyota’s maintenance schedule) for signs of wear or cracking.
• If you notice a fuel smell, a lingering gas odor after fueling, or frequent MIL illumination, address the EVAP system promptly to avoid more serious damage.
• Address small problems early: a loose hose, cracked vacuum line, or a failing purge valve is cheaper to fix early than a complete EVAP canister replacement.

Closing note on data: The data provided shows no NHTSA complaints for this issue in the specified model/year range and no recalls in the NHTSA database. This guide reflects those data constraints while offering standard EVAP diagnostic and repair guidance applicable to the P0440 code on the 2016-2023 Toyota Tacoma. If you work with a technician, they may also reference Toyota-specific TSBs or service notes if they appear during your vehicle’s diagnostics.