P0448: EVAP vent valve circuit shorted
EVAP vent control circuit shorted
Severity: Monitor
P0448 is an electrical fault in the EVAP vent valve circuit that mainly affects emissions testing.
It gets more serious if:
- Inspect soon: Get it checked sooner if the tank is hard to fill after the code appears, which can mean the vent valve is stuck closed.
P0448 in short
P0448 means the computer found a short in the wiring or coil of the EVAP vent valve, the valve that lets air into the vapor system. The usual causes are a failed vent valve or a shorted wire to it. The car normally drives fine but cannot complete its EVAP test.
The vent valve opens the EVAP system to fresh air and closes for leak tests. The computer drives it electrically.
TaT says a short to ground or power in that circuit can leave the valve stuck open or closed. On the Saab 9-2X procedure the code is set after two drive cycles with the fault.
That procedure checks the signal at the computer, the wiring for a short to battery, the valve resistance and the connector.
Most likely causes
These are general causes for this code across vehicles. None is specific to one make or model.
Cause 1: Vent valve with a shorted coil
Common general cause- Why it ranks here
- The Saab procedure measures valve resistance and replaces the valve if it is out of range.
- What would change this
- Rises if resistance is out of range. Falls if the valve reads normal.
Cause 2: Wiring shorted to battery or ground
Common general cause- Why it ranks here
- The Saab procedure tests the harness for a short to battery between computer and valve.
- What would change this
- Rises if the wiring shows a short. Falls if the wiring is clean.
Cause 3: Corroded connector or computer fault
Possible — needs testing- Why it ranks here
- The Saab procedure lists connector contact and computer replacement as last steps.
- What would change this
- Rises if the valve and harness test good. Falls if connector contacts are clean and the signal is normal.
What to test first
Start at step 1. Each result tells you what it means and where to go next.
Step 1: Read all codes and freeze-frame data and note other EVAP codes.
IfOther EVAP circuit codes are present
It meansLook for a shared wiring fault.
IfP0448 is alone
It meansTest the vent valve.
Step 2: Have the vent valve resistance and its wiring checked with a meter, following the vehicle's service data.
Warning:Vent valves sit near the fuel tank and fuel lines. Let a shop test them.
IfValve resistance is out of range
It meansThe valve is shorted.
IfValve is fine but wiring shows a short
It meansRepair the wiring.
IfBoth are fine
It meansCheck connectors and the computer.
Symptoms
- Check engine light
- Failed emissions test
How to fix
Step 1: Ask a shop to test the vent valve circuit; wiring near the fuel tank is best left to them.
On your vehicle
NissanYour car
2013–2018 · Sentra
Supported by vehicle dataNissan bulletin NTB14-044b names P0448. Service bulletin for 2013-2018 Sentra with the check engine light on and P0448. The summary does not say what the repair is. Whether it is still current is not verified.
NTB14-044bStatus unverified
MIL on with P0448 (Sentra)
2013–2018sentra · issued · NHTSA 10155157
Service bulletin for 2013-2018 Sentra with the check engine light on and P0448. The summary does not say what the repair is.
We couldn't confirm whether this bulletin is still current, so it doesn't count as confirmation.
InfinitiYour car
2019 · QX50
Supported by vehicle dataInfiniti bulletin ITB19-012 names P0448. For a 2019 QX50 with P0448 stored, the summary says to reprogram the engine computer if applicable. Whether it is still current is not verified.
2015–2019 · Q50
Supported by vehicle dataInfiniti bulletin ITB19-027 names P0448 (also listed for q60, qx60). If listed engine computer part numbers apply, the summary says to do the normal diagnosis and repair for the stored code, then reprogram the engine computer. Whether it is still current is not verified.
ITB19-012Status unverified
MIL on with P0448, EVAP canister vent control valve (QX50)
2019qx50 · issued · NHTSA 10161387
For a 2019 QX50 with P0448 stored, the summary says to reprogram the engine computer if applicable.
We couldn't confirm whether this bulletin is still current, so it doesn't count as confirmation.
ITB19-027Status unverified
MIL on with P0087, P0101, P0448 or P2008 (Q50, Q60, QX60)
2015–2019q50, q60, qx60 · issued · NHTSA 10165756
If listed engine computer part numbers apply, the summary says to do the normal diagnosis and repair for the stored code, then reprogram the engine computer.
We couldn't confirm whether this bulletin is still current, so it doesn't count as confirmation.
Related codes
P0448 questions
Is P0448 serious?
It usually does not affect how the car drives, but the EVAP monitor cannot finish and the car will fail an emissions test.
Sources and review
- P0448 fault code entry
- DTC P0448 Evaporative Emission Control System Vent Control Circuit Shorted (Saab 9-2X 2005, 2.0T)
- Nissan NTB14-044b: MIL on with P0448 (Sentra)
- Infiniti ITB19-012: MIL on with P0448, EVAP canister vent control valve (QX50)
- Infiniti ITB19-027: MIL on with P0087, P0101, P0448 or P2008 (Q50, Q60, QX60)
- Last reviewed
- Written by
- Saurabh K.
- Editorial review
- Pending
- Technician review
- Technician review pending
This page explains what a code usually means; it is not a substitute for a professional inspection. How we source and review · Report an error