Examining P0456 on Your 2021 Malibu
Your 2021 Malibu has triggered P0456—a very small EVAP leak (0.020-inch equivalent). The midsize sedan's 1.5L turbo four-cylinder (or available 2.0L turbo) uses GM's standard threaded gas cap and vent valve solenoid EVAP system. Basic warranty may have expired, but emissions coverage extends further.
Clues
- Check engine light on
- P0456 stored
- No performance symptoms
- Gas cap may feel loose
Causes Ranked
- Gas Cap Seal (High Likelihood): Worn after 4+ years. $10–$15.
- Vent Valve Solenoid (High Likelihood): GM's primary EVAP failure. $80–$220.
- Purge Solenoid (Medium Likelihood): Turbo heat wear. $80–$200.
- EVAP Hose (Medium Likelihood): Age-related degradation. $100–$240.
- FTP Sensor (Low Likelihood): Degraded sensitivity. $120–$260.
Diagnosis
- Replace the gas cap ($10–$15)
- Clear code and drive 50+ mixed miles
- Check vent valve solenoid if code returns
- Smoke test for persistent micro-leaks
Costs
- Gas cap: $10–$15
- Vent valve solenoid: $80–$220
- Purge solenoid: $80–$200
- EVAP hose: $100–$240
Can I Drive?
Yes. P0456 has zero performance or safety impact on your Malibu.
Warranty
GM's 3yr/36k likely expired in 2024. Federal emissions (8yr/80k) covers EVAP through 2029. Check your mileage—you may get this fixed for free at a Chevy dealer.