P0442 GMC Code - Evaporative Emission System Small Leak Detected
Quick Answer
The engine off natural vacuum test is the small leak detection diagnostic for the evaporative emission system. Common causes include Missing or loose fuel cap, Incorrect fuel filler cap used, Fuel filler cap remains open or fails to close. Severity is Low - monitor the vehicle and repair when practical. The vehicle can usually be driven if no severe symptoms are present, but symptoms should be checked before extended driving.
- What it means
- P0442 GMC indicates Evaporative Emission System Small Leak Detected.
- Common causes
- Common causes include Missing or loose fuel cap, Incorrect fuel filler cap used, Fuel filler cap remains open or fails to close.
- Severity
- Low - monitor the vehicle and repair when practical.
- Can I drive?
- The vehicle can usually be driven if no severe symptoms are present, but symptoms should be checked before extended driving.
Code P0442 GMC Description
What are the Possible Causes of the DTC P0442 GMC?
- Missing or loose fuel cap
- Incorrect fuel filler cap used
- Fuel filler cap remains open or fails to close
- Foreign matter caught in fuel filler cap
- Leaking EVAP Canister
- Leaking EVAP System Hose
- Leaking Fuel Tank
- Faulty Fuel Tank Pressure Sensor
How to Fix the DTC P0442 GMC?
Review the 'Possible Causes' above and visually examine the corresponding wiring harness and connectors. Check for damaged components and inspect connector pins for signs of being broken, bent, pushed out, or corroded.
Code Tech Notes
There is a factory service bulletin for all the models from 2000 through 2021. The factory states that there are seven critical connections that could likely lead to this DTC being set:
1. Purge tube to purge valve (at intake manifold)
2. Purge tube to chassis EVAP line (at the rear of the engine, near transmission)
3. Chassis EVAP line to canister (at canister)
4. Fuel tank load line to canister (at canister)
5. Vent valve line to vent valve (at vent valve)
6. Fuel tank load line jumper connection (near fuel tank)
7. Fuel tank cap is closed properly (at refuel compartment)
User Submitted Video
What is the Cost to Diagnose the Code?
Labor: 1.0
To diagnose the P0442 GMC code, it typically requires 1.0 hour of labor. Rates vary by location, vehicle, and shop. Many shops charge between $80–$150 per hour; dealerships and metro areas may be higher, independents may be lower.
Need more information about the P0442 GMC code?
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Information for Specific GMC Models
- P0442 2014 GMC Sierra — Evaporative Emission System Small Leak Detected
- P0442 2015 GMC Sierra — Evaporative Emission System Small Leak Detected
- P0442 2016 GMC Sierra — Evaporative Emission System Small Leak Detected
- P0442 2017 GMC Sierra — Evaporative Emission System Small Leak Detected
- P0442 2018 GMC Sierra — Evaporative Emission System Small Leak Detected
Frequently Asked Questions about P0442 GMC Code
1. What does OBDII code P0442 for GMC mean?
- OBDII code P0442 indicates that the Evaporative Emission System has detected a small leak.
2. What are the common symptoms of a P0442 code in a GMC vehicle?
- Common symptoms include the check engine light coming on and possible fuel odor around the vehicle.
3. What are the potential causes of a P0442 code in a GMC vehicle?
- Causes may include a loose or damaged gas cap, a leaking EVAP system hose, a faulty purge valve, or a cracked charcoal canister.
4. How serious is a P0442 code in a GMC vehicle?
- While a P0442 code may not affect the immediate drivability of the vehicle, it can lead to increased emissions and may cause the vehicle to fail an emissions test.
5. How can I diagnose a P0442 code in my GMC vehicle?
- Diagnosing a P0442 code often involves checking the gas cap for tightness, inspecting the EVAP system hoses for leaks, and using a smoke machine to pinpoint the source of the leak.
6. Can I repair a P0442 code in my GMC vehicle myself?
- Simple fixes like tightening or replacing the gas cap can often clear a P0442 code. However, diagnosing and repairing other potential causes may require professional assistance.
7. What are some tips for preventing a P0442 code in a GMC vehicle?
- Regularly inspecting the gas cap for tightness, avoiding overfilling the fuel tank, and keeping up with routine maintenance can help prevent a P0442 code from appearing.
8. How much does it typically cost to repair a P0442 code in a GMC vehicle?
- The cost of repairing a P0442 code can vary depending on the underlying cause. Simple fixes like replacing a gas cap may be inexpensive, while more complex repairs involving EVAP system components can be more costly.
9. Can a P0442 code clear on its own in a GMC vehicle?
- In some cases, a P0442 code may clear on its own after a few driving cycles if the underlying issue was temporary. However, it is recommended to diagnose and address the problem to prevent it from recurring.
10. Is it safe to continue driving with a P0442 code in a GMC vehicle?
- While a P0442 code may not immediately affect the performance of the vehicle, it is important to address the issue promptly to prevent potential emissions-related problems and ensure the vehicle remains in good working condition.
Discuss the causes and fixes for P0442 GMC OBDII Code
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If you already replaced the gas cap and the problem persist, you may need to have a shop check for a small leak on the system. Small leaks are difficult to find and special tools are needed to find them.
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