P0448 low

Evaporative Emission Control System Vent Control Circuit Shorted

The P0448 code means the vehicle's onboard diagnostic system has detected: Evaporative Emission Control System Vent Control Circuit Shorted. This is a low severity code.

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Keep driving?: Yes, but fix soon
DIY difficulty: moderate
Estimated cost: $60 - $280 (parts and labor)

Try This First ($8 Fix)

Stant 10838 OE Fuel Cap

A cracked or loose gas cap causes 60%+ of EVAP codes. This $8 replacement clears P0442, P0455, and P0457 more often than any other repair.

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Find the Leak

THIKPO Automotive Smoke Machine

If a new gas cap does not clear it, the leak is somewhere in the EVAP plumbing. A smoke machine finds the exact leak -- a cracked hose, bad seal, or stuck vent valve -- in minutes instead of guessing at parts.

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Clear the Code

ANCEL AD310 OBD-II Scanner

Clear the code after the repair. If the light stays off after 50 miles, you just saved $200+ in shop fees.

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Common Symptoms

Check Engine Light illuminated
Fuel tank pressure buildup
Difficulty refueling
Hissing sound when opening the gas cap
Failed emissions test

Probable Causes (Ranked by Likelihood)

Short to ground in vent valve wiring harness Very High
Internally shorted vent control solenoid High
Wiring harness damaged by road debris or corrosion Moderate
ECM vent valve driver circuit malfunction Low

Step-by-Step Diagnostic Procedure

Inspect vent valve wiring along the undercarriage for damage, chafing, or corrosion
Disconnect the vent valve and measure solenoid resistance -- a healthy coil typically reads about 20-50 ohms (check the factory spec for your vehicle); a reading near 0 ohms, or far below that spec, indicates an internally shorted solenoid
Check for short to ground on signal and power wires using a multimeter
Test with a known-good vent valve to isolate the problem
Inspect the ECM connector for water intrusion or corrosion on the vent valve pins

Common Fixes by Vehicle

What techs usually find when diagnosing P0448 on specific vehicles — tap your vehicle for the fix and the exact part:

2005-2018 Nissan Altima/Rogue 2.5L QR25DE moderate DIY

P0448 means the EVAP vent control valve circuit is shorted. On Nissan, the vent valve near the fuel tank canister shorts when moisture gets into the connector. Disconnect the valve and check if the code changes to P0447 (open) -- this confirms the valve is shorted internally. Replace with Dorman 911-502. Apply dielectric grease to the new connector.

Labor: 30-45 min

Common fix part Dorman EVAP Canister Vent Valve View on Amazon→ Compare fitment at PartsGeek→

2007-2019 Toyota Camry/Highlander 2.5L/3.5L moderate DIY

The EVAP canister close valve wiring can short to ground where it passes along the underbody. Inspect the harness from the ECM to the canister valve for pinched or chafed wires against frame rails. Repair damaged wiring and wrap with heat-resistant split loom. If the valve coil resistance is below 10 ohms, replace the valve assembly.

Labor: 45 min - 1.5 hours

Common fix part Dorman EVAP Vent Valve View on Amazon→ Compare fitment at PartsGeek→

2013-2020 Nissan Pathfinder/Murano 3.5L VQ35DE moderate DIY

On larger Nissan vehicles, the vent valve harness runs a longer path and is more susceptible to chafing. Check where the harness crosses the rear subframe mounting points. A short to ground at these contact points is common. Repair with solder and heat-shrink tubing. If the valve itself is shorted, replace with the OE vent valve assembly.

Labor: 1-2 hours

Common fix part Dorman EVAP Canister Vent Valve View on Amazon→ Compare fitment at PartsGeek→

Frequently Asked Questions

Can I drive with code P0448?

Yes. This code will not affect engine performance or drivability. However, a stuck vent valve can cause fuel tank pressure issues and difficulty refueling.

What is the difference between P0447 and P0448?

P0447 indicates an open circuit (broken connection) in the vent control circuit, while P0448 indicates a short circuit (wire grounding out or internally shorted solenoid).

Can I replace the vent valve myself?

The vent valve is accessible on most vehicles but may require raising the vehicle. It is typically a bolt-on part near the charcoal canister with one electrical connector and one or two hose connections.