P0442 on 2010-2016 Cadillac SRX: Causes and Fixes for a Small EVAP Leak

What's Unique About the 2010-2016 Cadillac SRX

On the second-generation Cadillac SRX, the P0442 code is a frequently discussed issue. While the causes are typical for many GM vehicles, forum discussions and mechanic videos often point towards the EVAP purge and vent solenoids as common failure points after the gas cap has been ruled out. GM has also issued technical service bulletins, like 21-NA-124, which provide specific diagnostic strategies for P0442 on this and similar platforms, indicating it's a known pattern.

Diagnostic Flowchart

Tap your situation to follow the diagnostic path that matches what you're seeing on this vehicle.

Symptoms You May Notice

• Check Engine Light is on
• A faint smell of fuel, particularly around the outside of the car
• Difficulty starting immediately after refueling. This happens when a stuck-open purge valve allows fuel vapors to flood the engine intake while the tank is being filled.
• Intermittent rough idle at a stop. A leaking purge valve can create a small vacuum leak, causing the engine idle to fluctuate briefly.

Most Likely Causes

1. Loose or Faulty Gas Cap 🔴 High Probability The gas cap is the most frequently handled part of the EVAP system, and its seal can wear out, get damaged, or the cap can simply be left loose after refueling. Using a non-OEM cap can also cause sealing issues.
   How to confirm: Remove the gas cap, inspect the rubber O-ring seal for cracks, stiffness, or damage. Check the filler neck for rust or debris that could prevent a good seal. Reinstall the cap, ensuring it clicks several times. Clear the code and drive for a few days to see if it returns.
   Typical fix: Tighten the cap or replace it with a new OEM-spec cap for best results.
   Est. part cost: $15-$40
2. Faulty EVAP Purge Valve/Solenoid 🟡 Medium Probability This valve is located in the engine bay and cycles frequently, leading to wear. It can get stuck partially open, causing a small, constant leak that the system detects during its self-test. This is a very common failure point on GM V6 engines.
   How to confirm: The valve is located on the engine. With the engine off, disconnect the hoses and try to blow through it. It should be normally closed, so if air passes through, it has failed. A professional diagnosis involves using a scan tool to command the valve open and closed while monitoring system vacuum.
   Typical fix: Replace the purge valve solenoid. This is generally accessible on the passenger side of the engine, near the back.
   Est. part cost: $20-$60
3. Faulty EVAP Vent Solenoid/Valve 🟡 Medium Probability This component is located underneath the vehicle near the charcoal canister and is exposed to road debris, salt, and moisture, which can cause the internal solenoid to fail or stick, preventing the system from sealing for its pressure test.
   How to confirm: A smoke test is the most effective method. Smoke is introduced into the EVAP system, and if the vent solenoid is leaking when commanded closed by a scan tool, smoke will be seen exiting from it. It can also be bench-tested by applying 12V power; it should click and close. If it doesn't click or remains open, it's faulty.
   Typical fix: Replace the vent solenoid. It is typically mounted on or near the EVAP charcoal canister under the car, near the driver's side.
   Est. part cost: $40-$100
4. Cracked or Disconnected EVAP Hose ⚪ Low Probability Over time, the rubber and plastic hoses in the EVAP system can become brittle from heat cycles and age, leading to small cracks, especially at connection points.
   How to confirm: Visually inspect all accessible EVAP lines running from the gas tank, to the charcoal canister, and up to the engine. A smoke test is the definitive way to find a small hose leak that isn't visible. TSB 21-NA-124 specifically advises checking for unseated or damaged tube connections first.
   Typical fix: Replace the cracked section of hose or the entire line assembly.
   Est. part cost: $10-$50

Rare But Worth Checking

• Leaking Charcoal Canister: The plastic housing of the canister itself can develop hairline cracks from age or impact, causing a leak. This is usually found with a smoke test after all other components have been checked and confirmed to be working.
• Leaking Fuel Tank or Filler Neck: Rust on the metal fuel filler neck where the gas cap seals can create an uneven surface, preventing the cap from sealing properly even if the cap itself is new. A leak in the fuel tank itself is rare but possible, especially in areas with heavy road salt use.

Diagnosis Steps

1. Inspect the gas cap. Ensure it is tight. If the seal looks cracked or worn, replace it, preferably with an OEM part.
2. If the code returns, perform a visual inspection of all accessible EVAP hoses in the engine bay and under the vehicle for obvious cracks or disconnections, per TSB 21-NA-124.
3. Locate the EVAP purge valve in the engine bay. With the engine off, disconnect the hoses and try blowing through the valve. It is a normally-closed valve, so if any air passes through, it is defective and must be replaced.
4. If the above steps don't reveal the issue, the most effective next step is a smoke test. A smoke machine forces low-pressure smoke into the EVAP system via the service port, and the leak will be visible where the smoke escapes.
🎬 Watch: How to perform a smoke test to find leaks.
5. During the smoke test, pay close attention to the purge valve, the vent solenoid (under the car), the charcoal canister, and all hose connection points. A scan tool should be used to command the vent valve closed to properly seal the system for the test.
6. If a valve is suspected, use a capable scan tool to command the purge and vent valves to open and close while monitoring the fuel tank pressure sensor to confirm their mechanical operation.

Parts You'll Likely Need

• Fuel Cap (OEM #13502507) — This is the most common failure point due to frequent use and wear on the seal. An improper seal is a direct cause of a P0442 code.
  Trusted brands: ACDelco (OEM)
  OEM price range: $20-$40
  Aftermarket price range: $15-$30
• Vapor Canister Purge Valve / Solenoid (OEM #13575704 (may be superseded by 84148825)) — This valve gets stuck open, causing a constant small leak. It's a very common fix for P0442 and related codes like P0496.
  Trusted brands: ACDelco, Bosch, Dorman
  OEM price range: $30-$60
  Aftermarket price range: $20-$45
• Vapor Canister Vent Valve / Solenoid (OEM #25932571 (may be superseded by 23481275)) — Located under the car, this valve can fail due to exposure to the elements, getting stuck open or closed. It's a primary suspect when the gas cap and purge valve are good.
  Trusted brands: ACDelco (OEM), Dorman
  OEM price range: $50-$100
  Aftermarket price range: $40-$80

Related Codes That Often Appear With This One

• P0455 — This indicates a large EVAP leak. The same faulty component (like a stuck-open valve) can sometimes trigger a small leak code one day and a large leak code the next. TSB #21-NA-124 specifically mentions diagnosing both codes with the same procedure.
• P0449 — This code points specifically to a fault in the EVAP vent solenoid control circuit. If you see P0442 and P0449 together, the vent solenoid or its wiring is almost certainly the problem.
• P0496 — This code indicates 'EVAP Flow During a Non-Purge Condition,' which almost always points to a purge valve that is stuck open, allowing fuel vapor to flow when it shouldn't. It's very common to see this with P0442.

Technical Service Bulletins (TSBs) & Recalls

• 21-NA-124: Provides diagnostic tips for EVAP leaks related to codes P0442 and/or P0455. It advises a specific order of operations: 1) Check all EVAP lines are seated and undamaged. 2) Check vent valve for stuck open position. 3) Investigate purge valve.
• PIT4943D: Advises technicians to use an Evaporative Emissions System Tester (smoke machine) for diagnosing P0442, highlighting that visual inspection may not be sufficient.
• PI0523A: A preliminary bulletin for some GM models that mentions checking for a rolled-over rubber insulator in the fuel filler pocket, which can prevent the gas cap from sealing correctly.

Platform-Specific Known Issues

• Vent Solenoid Location: The EVAP Vent Solenoid is located under the vehicle, roughly below the driver's side door, mounted to the EVAP canister. It can be tricky to access without raising the vehicle. The part often twists to lock into the canister.
• Purge Valve Location: The EVAP Purge Valve on the 3.0L and 3.6L V6 engines is located on the back/passenger side of the engine, near the throttle body, tucked under the engine cover. A forum user on TexAgs.com confirmed finding it there and that replacing it fixed their P0442 code.

Mechanic-Grade Diagnostic Values

• Fuel Tank Pressure (FTP) Sensor Signal Voltage — expected: 0.1V - 4.9V. A reading of ~1.5V is common with the key on, engine off, and the gas cap removed (at atmospheric pressure).. Failure: A voltage that is stuck at a specific value and does not change when pressure/vacuum is applied, or a reading outside the 0.1-4.9V range.

Scan Tool Commands That Help

• GDS2 (GM Techline): EVAP Purge/Seal — This function is used to command the vent solenoid closed to seal the system and then command the purge solenoid to apply engine vacuum. The technician can then monitor the Fuel Tank Pressure sensor to see if the system holds vacuum, diagnosing a leak.
• GDS2 (GM Techline): EVAP Canister Vent Solenoid Valve Test — Allows the technician to cycle the vent solenoid on and off multiple times. This can help identify an intermittently sticking valve that may not be caught with a single test or visual inspection, as recommended in TSB 21-NA-124.

Wiring & Ground Locations

• G100 — Rear of the engine compartment.. A poor ground here could affect components controlled by the Engine Control Module (ECM), which manages the EVAP system.
• G201 / G301 — Located in the driver's side left kick panel area.. These are primary body grounds. While less likely to be the direct cause, a fault here can create unpredictable electrical issues in various systems, including the Body Control Module which communicates with the ECM.
• EVAP Canister Vent Solenoid Connector — Under the vehicle, on the EVAP canister, typically below the driver's side rear passenger area.. This is the electrical connection for the vent valve. It is exposed to road spray and corrosion, which can cause a P0449 (vent circuit fault) and contribute to a P0442 if the valve isn't operating correctly.

Real Owner Repair Stories

• TexAgs.com forum user 'ChemEAg08' (2011 Cadillac SRX) — P0442 code, intermittent hard start (1 out of 20 times).
  ❌ Tried (didn't work) Replaced a different solenoid valve (likely the vent solenoid), Tried a different gas cap
  ✅ What actually fixed it Replaced the EVAP Purge Valve. The owner confirmed the old valve was leaking air when it should have been closed. The part was located on the passenger side, behind the engine.

"I Checked Everything" — The Actual Cause

• A valve (purge or vent) can sometimes pass a pressure-based smoke test but fail under vacuum. The EVAP system's self-test works by pulling a slight vacuum. A faulty valve seal might hold against the positive pressure of a smoke machine but allow air to leak in under vacuum, causing the P0442 code to set. A technician can test for this by applying vacuum directly to the valve with a hand pump to see if it holds.

OEM Part Supersession History

• 13575704 → 84148825 — Standard part revision by the manufacturer.
• 25932571 → This part number supersedes older PNs 10382105, 15750484, and 22728634. It may itself be superseded by 23481275 per some parts catalogs. — Part consolidation and design updates over multiple vehicle platforms.
  Heads up: Always verify the correct part for your specific VIN, as multiple revisions exist.

Model Year Variations Within This Range

• 2010-2011 vs 2012-2016: The primary engine changed from a 3.0L V6 (LF1) in 2010-2011 to a 3.6L V6 (LFX) in 2012-2016. While the function and location of EVAP components are broadly similar, the specific part numbers for items like the purge valve and the routing of hoses may differ.