P0448 OBD-II Trouble Code: Evaporative Emission Control System Vent Control Circuit Shorted

Our certified mechanics come to you · Get a fair and transparent estimate upfront

Red-stars EXCELLENT RATING ON

Cost of diagnosing the P0448 code

P0448 is a diagnostic trouble code (DTC) for "Evaporative Emission Control System Vent Control Circuit Shorted". This can happen for multiple reasons and a mechanic needs to diagnose the specific cause for this code to be triggered in your situation. Our certified mobile mechanics can come to your home or office to perform the Check Engine Light diagnostic for $114.99 . Once we are able to diagnose the problem, you will be provided with an upfront quote for the recommended fix and receive $20.0 off as a credit towards the repair. All our repairs are backed by our 12-month / 12,000-mile warranty.

Cars Estimate Credit towards follow-up repair Earliest Availability
Ford $114.99 $20.0
Toyota $114.99 $20.0
BMW $124.99 $20.0
SCHEDULE P0448 DIAGNOSTIC Get a fair and transparent estimate upfront

P0448 OBD-II Trouble Code: Evaporative Emission Control System Vent Control Circuit Shorted

Diagnostic Trouble Code (DTC): P0448

P0448 code definition

The P0448 code is stored when the powertrain control module (PCM) detects that the circuit for the evaporative emission control system’s vent has shorted, or that the valve for this system is stuck in the closed position.

What the P0448 code means

When gas sits in the gas tank, it emits vapor. As you drive your vehicle, the evaporative emission control system’s vent opens up to allow those vapors to circulate through to the charcoal canister, the outside of the vehicle, or the engine’s intake manifold (depending on what kind of vehicle you have). If this vent valve is stuck closed or there is a short in its circuit preventing it from opening, the PCM will store a P0448 code, and the Check Engine Light will come on.

What causes the P0448 code?

Some of the most common reasons that a P0448 code may be stored include:

  • A damaged or defective vent valve
  • An improperly installed or defective fuel cap
  • A clogged or faulty charcoal canister
  • A damaged purge control solenoid
  • Cracks in the fuel vapor or vacuum hoses
  • A problem with the wiring or circuit for the vent valve
  • A problem with the PCM (rare)

What are the symptoms of the P0448 code?

In most cases, the only noticeable symptom will be the illuminated Check Engine Light. However, even though other symptoms may not be in evidence, there will likely be other related codes stored by the PCM, as well.

How does a mechanic diagnose the P0448 code?

The first step in diagnosing a P0448 code is to use an OBD-II scanner to read any and all codes stored by the PCM. If other related codes are stored, they should be dealt with first. Then, the mechanic will move on to diagnose the issues causing the P0448 code to be stored.

They may start by checking the fuses, as a blown fuse could be preventing the vent solenoid from operating. After checking the fuses, they’ll check the circuit for any chafed, corroded, or otherwise damaged wires in the wiring harness, and they’ll check the connectors to ensure they’re not corroded and that all connections are solid.

Using an ohmmeter, they may check that the voltage is consistent throughout the circuit. Upon resolving any issues with the vent valve and/or its circuit, they’ll clear all codes and then retest the system to ensure that the code isn’t saved again.

Common mistakes when diagnosing the P0448 code

Often, the problem can be traced to a leak in a vacuum hose or a problem with the fuel cap. In many cases, though, inexperienced mechanics and vehicle owners will miss these potentially simple fixes and spend a lot of time and money trying to make repairs that won’t actually fix the problem.

What repairs can fix the P0448 code?

As we mentioned, some of the most common causes for a P0448 code to be stored involve a faulty gas cap and/or a leak in one of the hoses. Replacing these components may solve the problem without any further work. Other common solutions include:

  • Replacing a defective vent valve
  • Repairing or replacing a clogged or cracked charcoal canister
  • Replacing a damaged purge control solenoid
  • Repairing or replacing wiring or connectors in the vent valve’s circuit
  • Repairing or replacing a faulty PCM (rare)

Additional comments for consideration regarding the P0448 code

If you have a Chrysler, Jeep, or Dodge vehicle that has set a P0448, there’s a good chance that you have a bad vent. GM has released an improved valve assembly to handle this problem, as well. Whatever type of vehicle you have, if you want to ensure that your vehicle passes an OBD-II emissions test, you’ll have to get this issue taken care of and clear all codes from your PCM.

Need help with a P0448 code?

YourMechanic offers certified mobile mechanics who will come to your home or office to diagnose and repair your vehicle. Get a quote and book an appointment online or speak to a service advisor at 1-800-701-6230.

Check Engine Light
EVAP (Evaporative Emission Control) system
trouble codes
P0448

No more waiting rooms! Our mechanics will come to you to diagnose and fix the P0448 code.

SCHEDULE P0448 DIAGNOSTIC
Get a $50 credit for the follow-up repair

Recent Check Engine Light is on Inspection reviews

Excellent Rating

(7400)

Rating Summary
6879
249
58
41
173
6879
249
58
41
173
 at YourMechanic

David

13 years of experience
393 reviews
David
13 years of experience
Chevrolet Malibu L4-2.4L - Check Engine Light is on Inspection - Marietta, Georgia
He explained everything to me in detail on what I needed to know about my car. Definitely recommend him for getting the job done.
 at YourMechanic

Raymond

37 years of experience
402 reviews
Raymond
37 years of experience
Toyota Camry L4-2.2L - Check Engine Light is on - Las Vegas, Nevada
Raymond did a great job however I was charged for two hours labor and he was only here less than 45 minutes. should I expect this on future appointments with your mechanic ?
 at YourMechanic

Shane

17 years of experience
217 reviews
Shane
17 years of experience
Volkswagen EuroVan V6-2.8L - Check Engine Light is on Inspection - Austin, Texas
Arrived on time. Explained the issues he found and how he will fix it. I have parts on order and will schedule an appointment to have Shane install the parts when they arrive.
 at YourMechanic

Kanstantsin

19 years of experience
51 reviews
Kanstantsin
19 years of experience
Ford F-150 V8-4.6L - Check Engine Light is on Inspection - Littleton, Colorado
Kanstantsin arrived early. Was very courteous and professional. Will highly recommend to anyone. Thank you Kanstantsin.


More related articles

P0709 OBD-II Trouble Code: Transmission Range Sensor Circuit Malfunction
P0709 P0709 code definition The P0709 code is known as Transmission Range Sensor Circuit Intermittent. What the P0709 code means The meaning of P0709 varies slightly among makes and models, but in general, this code indicates that the PCM (powertrain...
P0357 OBD-II Trouble Code: Ignition Coil G Primary/Secondary Circuit Malfunction
P0357 P0357 code definition When the P0357 code is stored, it means that the PCM has detected one or more ignition coils (https://www.yourmechanic.com/services/ignition-coil-replacement) is faulty to some degree. What the P0357 code means Most vehicles with an OBD-II system utilize...
P0350 OBD-II Trouble Code: P0350 Ignition Coil Primary/Secondary Circuit Malfunction
P0350 code refers to an input problem relating to the engine's ignition coils which effects the vehicle's engine performance.

Related questions

Engine misfiring 2003 Honda CR-V
Misfires (https://www.yourmechanic.com/article/is-it-safe-to-drive-with-a-misfiring-engine) can be caused by several things. I would first check for vacuum leaks (https://www.yourmechanic.com/article/is-it-safe-to-drive-with-a-vacuum-leak), then I would pull the plugs to see if they need replacing. It is possible that have a fuel system concern, but I would...
Getting error codes P0599 and P0171. Ive cleaned the O2 sensors but have no idea where to go from here.
Hello. Code P0599 is the code for an issue with the thermostat heater control circuit, while P0171 is for a lean condition on bank 1. P0599 is set when the computer detects that there is an issue with the electronically...
Intake manifold runner control stuck
The IMRC (Intake manifold runner control) (https://www.yourmechanic.com/article/symptoms-of-a-bad-or-failing-intake-manifold-runner-control) is a vacuum modulated solenoid that operates a butterfly valve in the intake manifold. The purpose is to optimize the air/fuel ratio for best fuel economy and drivability. Sometimes the code will refer...

How can we help?

Our service team is available 7 days a week, Monday - Friday from 6 AM to 5 PM PST, Saturday - Sunday 7 AM - 4 PM PST.

1 (855) 347-2779 · hi@yourmechanic.com