P0440 Buick Code - Evaporative Emission System
Quick Answer
The Powertrain Control Module (PCM) tests the Evaporative Emission (EVAP) system for the following conditions: - Large and small leaks - Excess vacuum - Purge flow during non-commanded conditions - Fuel Level and Fuel Pressure sensor faults - EVAP Purge and Vent Valve faults The PCM monitors the Fuel Tank Pressure sensor in order to determine the level of vacuum/pressure in the EVAP 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
- P0440 Buick indicates Evaporative Emission System.
- 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 P0440 Buick Description
- Large and small leaks
- Excess vacuum
- Purge flow during non-commanded conditions
- Fuel Level and Fuel Pressure sensor faults
- EVAP Purge and Vent Valve faults
The PCM monitors the Fuel Tank Pressure sensor in order to determine the level of vacuum/pressure in the EVAP system. The PCM commands both the EVAP Purge Solenoid and the EVAP Vent Valve ON when the conditions are met in order to apply an engine vacuum to the EVAP system. The PCM commands the EVAP Purge Solenoid OFF once the system has reached a predetermined level of vacuum. This test verifies if a vacuum can be achieved in the EVAP system. Failure to develop a vacuum may be caused by a large leak or a restriction.
What are the Possible Causes of the DTC P0440 Buick?
- 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
- EVAP canister or fuel tank leaks
- EVAP system hose leaking
- Fuel tank leaking
- Faulty vent solenoid
- Faulty EVAP purge switch
How to Fix the DTC P0440 Buick?
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
What is the Cost to Diagnose the Code?
Labor: 1.0
To diagnose the P0440 Buick 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 P0440 Buick code?
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Need Help with the Code?
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Frequently Asked Questions about P0440 Buick Code
No Frequently Asked Questions about P0440 Buick Code found.
Discuss the causes and fixes for P0440 Buick OBDII Code
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2013 Verano 55400 miles the PO440 code came on the code reader. Mechanic said the oil is probably contaminated and when I get the oil changed tell the company to use bottled oil not bulk. I just had the oil changed and told him so then he said it is probably the sensor needs to be changed he looked it up for cost and said that both seniors had be changed at same time they cost 89.00 each and 90.00 labor. Did not have them changed at this point.
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First of all, the P0440 code has nothing to do with engine oil, and if the oil is bottle or in a drum does not change anything.
Do no change anything yet, just make sure the gas cap is tight and then clear the code. You can clear the code with a OBDII scanner or by disconnecting the car battery for about 30 minutes.
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