OBD-II Code
P0448
Severity
Not yet reviewed
Nobody on our side has assessed this code yet, so we are not going to guess at how serious it is.
Can you drive it
We cannot say
Treat it as unknown until a shop reads it with live data. If the check-engine light is FLASHING, stop driving as soon as it is safe to — that means an active misfire, whatever the code.
Indicative cost (USD)
$50–$280
From this code's diagnostic notes. Varies by vehicle, diagnosis, parts, and local labor. This is not a repair quote.
P0448 is the opposite electrical failure from P0447 - the ECM commanded the EVAP vent valve and detected a short circuit on the control side, either the solenoid coil is shorted internally, the control wire is shorted to ground or to 12V, or the PCM ground-side driver has failed shorted.
How a shop works this
Work from evidence to part, not the other way round. A code names a circuit or a symptom; it does not name the part that failed.
Note every code that is set, not just this one.
Codes that appear together usually narrow the cause faster than any one of them read alone.
Read the freeze frame — the conditions the fault was recorded under.
Cold or warm, idle or load, road speed and engine speed. A fault that only appears cold is a different fault from one that only appears under load, even with the same code on the scanner.
Confirm the fault is current rather than history.
Clear the code and see whether it returns under those same conditions. A code that does not come back may have been logged during a repair, a flat battery, or a bad connection that has since been disturbed.
Then follow the diagnostic notes further down this page, in the order they are written.
They are written in the order a shop works this code, cheapest checks first. Where they name a component, inspect its wiring and connector before replacing it.
If the code comes back after a repair, the underlying fault is still there. That is the point to bring in a scanner with live data and freeze-frame, or a shop that has one.
Common symptoms
- Check engine light
Read the full diagnostic procedureP0448 is the opposite electrical failure from P0447 - the ECM commanded the EVAP vent valve and detected a short circuit on the control side, either…
P0448 is the opposite electrical failure from P0447 - the ECM commanded the EVAP vent valve and detected a short circuit on the control side, either the solenoid coil is shorted internally, the control wire is shorted to ground or to 12V, or the PCM ground-side driver has failed shorted.
Cheapest-first ladder
- locate the vent valve at the canister and unplug the connector.
- Measure solenoid coil resistance across the two pins - a healthy vent solenoid reads 20 to 80 ohms; a short reads under 5 ohms (the coil is internally fused together) and trips the ECM short-circuit protection.
- If the solenoid resistance is in spec, key-on backprobe the harness side and verify the control wire is not shorted to chassis ground (should read open with connector unplugged, key-off) or to 12V (should read 0V with connector unplugged, key-on engine off).
- Inspect the connector and pigtail for chafed insulation where the wires cross sharp metal edges on the frame rail or the canister bracket - chafed-through insulation against bare metal is the dominant root cause on truck platforms.
- The expensive misdiagnosis is replacing the PCM for a shorted driver when the actual fault is a $4 piece of harness loom and 15 minutes with electrical tape - always isolate the short to the solenoid, the wiring, or the PCM before reaching for a control module.
Vehicle-specific patterns2007-2014 GM full-size trucks (Silverado, Sierra, Suburban, Tahoe) throw P0448 from rodent damage that simultaneously shorts the vent valve control w…
- 2007-2014GM full-size trucks (Silverado, Sierra, Suburban, Tahoe) throw P0448 from rodent damage that simultaneously shorts the vent valve control wire to ground - mice chew through the insulation and the bare conductor touches the canister bracket.
- 2009-2014Ford F-150 has the same rodent-induced short pattern on the frame-rail harness.
- 2007-2014Toyota Tundra/Sequoia 5.7L throws P0448 from internally shorted vent solenoid coils after long-term road salt and water intrusion - common on trucks driven on salted northern roads.
- 2009-2018RAM 1500 throws P0448 from chafed vent valve wiring against the fuel tank strap. Subaru EJ-series (Outback, Forester, Legacy) sees vent valve coil shorts from heat-aged insulation when the solenoid is mounted near the exhaust manifold. The damage pattern across all rodent-affected platforms is identical: check the canister area for droppings, chewed insulation, and nest material before the trip back to the shop.
Estimated repair$50 to $280.
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