P0455 on Cadillac Lyriq: Symptoms, Causes & DIY Fix
Official technical diagnostic wire for fault code P0455 (P0455: Evaporative Emission Control System Leak Detected (Gross Leak)) specifically affecting Cadillac Lyriq vehicles equipped with Ultium Dual Motor AWD (500HP / 450 lb-ft) / Single Motor RWD (340HP).
1. Symptoms of P0455 on Cadillac Lyriq
When the Engine Control Module (ECM/PCM) on your Cadillac Lyriq (Ultium Dual Motor AWD (500HP / 450 lb-ft) / Single Motor RWD (340HP)) logs fault code P0455, drivers commonly observe:
2. Most Likely Causes on Cadillac Lyriq
Historical warranty claims and technical repair bulletins for Cadillac Lyriq point to the following failure distribution:
3. Step-by-Step DIY Repair Guide for Cadillac Lyriq
Remove gas cap, inspect rubber O-ring for cracks, tighten until it clicks 3 times. on the Cadillac Lyriq equipped with Ultium Dual Motor AWD (500HP / 450 lb-ft) / Single Motor RWD (340HP).
If the cap rubber is dried or cracked, replace with genuine OEM cap ($15). on the Cadillac Lyriq equipped with Ultium Dual Motor AWD (500HP / 450 lb-ft) / Single Motor RWD (340HP).
Disconnect electrical plug and vacuum hose. Apply 12V; verify valve seals tight when unpowered. on the Cadillac Lyriq equipped with Ultium Dual Motor AWD (500HP / 450 lb-ft) / Single Motor RWD (340HP).
Check vent valve for road salt corrosion or spider nest clogs. on the Cadillac Lyriq equipped with Ultium Dual Motor AWD (500HP / 450 lb-ft) / Single Motor RWD (340HP).
Pump mineral oil smoke into EVAP port to reveal any hairline cracked lines. on the Cadillac Lyriq equipped with Ultium Dual Motor AWD (500HP / 450 lb-ft) / Single Motor RWD (340HP).
4. Cadillac Lyriq P0455 FAQs
What causes code P0455 to trigger on a Cadillac Lyriq?
On the Cadillac Lyriq (Ultium Dual Motor AWD (500HP / 450 lb-ft) / Single Motor RWD (340HP)), P0455 is most frequently caused by Missing, loose, or cracked gas cap seal or Faulty EVAP purge control solenoid. Factory sensor degradation or wiring harness wear near the engine bay are common factors.
Can I safely drive my Cadillac Lyriq with code P0455?
Yes. Completely safe to drive, but emissions test will fail. Given that P0455 carries a Low severity rating on Cadillac vehicles, we advise performing diagnostic scanning via the OBD-II port located under driver steering column beneath knee bolster before extended highway driving.
Where is the diagnostic port located on the Cadillac Lyriq?
The 16-pin OBD-II DLC connector on the Cadillac Lyriq is situated under driver steering column beneath knee bolster. It requires no special tools to plug in a standard scanner.
How much does it cost to fix P0455 on a Cadillac Lyriq?
DIY replacement parts typically range between $15 - $250 (DIY: $15 - $50). If serviced at an authorized Cadillac dealership, expect an additional $120–$250 in professional labor based on their $165/hr hourly rate.