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P0455 on Cadillac CT5: Fix & DLC Location

Factory diagnostic troubleshooting wire for fault code P0455 (P0455: Evaporative Emission Control System Leak Detected (Gross Leak)) specifically on the Cadillac CT5 (2020–2026, 2.0L Twin-Scroll Turbo (237HP) / 3.0L Twin-Turbo V6 (CT5-V 360HP)).

Cadillac CT5
DIY Parts Estimate
$15 - $250 (DIY: $15 - $50)
CT5 OEM Fitment
Shop Labor Quote
$180 – $380
Based on $165/hr labor
Drivability Status
Drivable (Short Trip)
Low urgency level
Est. DIY Time
45 – 90 Min
Basic hand tools
Check P0455 On Another Cadillac Model:
Cadillac EscaladeCadillac Escalade-VCadillac CT5Cadillac CT5-V BlackwingCadillac XT5Cadillac Lyriq

1. Symptoms of P0455 on Cadillac CT5

When the Engine Control Module (ECM/PCM) on your Cadillac CT5 (2.0L Twin-Scroll Turbo (237HP) / 3.0L Twin-Turbo V6 (CT5-V 360HP)) logs fault code P0455, drivers commonly observe:

Check Engine Light on on Cadillac CT5 (2.0L Twin-Scroll Turbo (237HP) / 3.0L Twin-Turbo V6 (CT5-V 360HP))
Gas cap loose warning message on dashboard on Cadillac CT5 (2.0L Twin-Scroll Turbo (237HP) / 3.0L Twin-Turbo V6 (CT5-V 360HP))
Slight fuel vapor odor near rear of vehicle on Cadillac CT5 (2.0L Twin-Scroll Turbo (237HP) / 3.0L Twin-Turbo V6 (CT5-V 360HP))
Cadillac CT5 OBD-II Port Location
The 16-pin diagnostic connector is located Driver footwell lower bezel near hood release. Plug in your scan tool to verify freeze-frame sensor values.

2. Most Likely Causes on Cadillac CT5

Historical warranty claims and technical repair bulletins for Cadillac CT5 point to the following failure distribution:

55%
Missing, loose, or cracked gas cap seal (Cadillac OEM Part)
25%
Faulty EVAP purge control solenoid (Cadillac OEM Part)
12%
Stuck open EVAP vent valve (Cadillac OEM Part)
8%
Cracked EVAP charcoal canister vapor hose (Cadillac OEM Part)

3. Step-by-Step DIY Repair Guide for Cadillac CT5

01
Inspect and Tighten the Gas Cap

Remove gas cap, inspect rubber O-ring for cracks, tighten until it clicks 3 times. on the Cadillac CT5 equipped with 2.0L Twin-Scroll Turbo (237HP) / 3.0L Twin-Turbo V6 (CT5-V 360HP).

Required Tool: None
02
Replace Gas Cap with OEM Replacement

If the cap rubber is dried or cracked, replace with genuine OEM cap ($15). on the Cadillac CT5 equipped with 2.0L Twin-Scroll Turbo (237HP) / 3.0L Twin-Turbo V6 (CT5-V 360HP).

Required Tool: New OEM Gas Cap
03
Test EVAP Purge Solenoid Under Hood

Disconnect electrical plug and vacuum hose. Apply 12V; verify valve seals tight when unpowered. on the Cadillac CT5 equipped with 2.0L Twin-Scroll Turbo (237HP) / 3.0L Twin-Turbo V6 (CT5-V 360HP).

Required Tool: 12V Probe, Vacuum Pump
04
Inspect EVAP Canister Vent Valve Near Gas Tank

Check vent valve for road salt corrosion or spider nest clogs. on the Cadillac CT5 equipped with 2.0L Twin-Scroll Turbo (237HP) / 3.0L Twin-Turbo V6 (CT5-V 360HP).

Required Tool: Flashlight, Jack Stands
05
Smoke Test EVAP System

Pump mineral oil smoke into EVAP port to reveal any hairline cracked lines. on the Cadillac CT5 equipped with 2.0L Twin-Scroll Turbo (237HP) / 3.0L Twin-Turbo V6 (CT5-V 360HP).

Required Tool: EVAP Smoke Machine

Other Common Fault Codes on Cadillac CT5

Frequently diagnosed powertrain, emissions, and sensor trouble codes logged on the Cadillac CT5:

4. Cadillac CT5 P0455 FAQs

What causes code P0455 to trigger on a Cadillac CT5?

On the Cadillac CT5 (2.0L Twin-Scroll Turbo (237HP) / 3.0L Twin-Turbo V6 (CT5-V 360HP)), P0455 is most frequently caused by Missing, loose, or cracked gas cap seal or Faulty EVAP purge control solenoid.

Where is the OBD-II port located on my Cadillac CT5?

On the Cadillac CT5, the 16-pin DLC diagnostic connector is located Driver footwell lower bezel near hood release. Plug in any standard OBD-II scanner with the ignition in the ON position to read freeze-frame parameters.

Can I safely drive my Cadillac CT5 with code P0455?

Yes. Completely safe to drive, but emissions test will fail. Given that P0455 carries a Low severity rating, we advise avoiding heavy towing or aggressive throttle inputs until sensor readings are verified.