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P0440 Error Code on 2001 Pontiac Firebird V6: Diagnosis and Solutions

Model: Pontiac Firebird Fault Code: P0440 Posted: 2006-10-02 18:49

Vehicle: 2001 Pontiac Firebird V6 3.8L, 83,000 miles I've been experiencing the P0440 error code on my 2001 Pontiac Firebird for several days. The code indicates a failure in the Evaporative Emission Control System (EVAP). At AutoZone, I was advised that common causes include a misaligned gas cap or a cracked seal — however, upon inspection, my gas cap's seal was indeed cracked, so I replaced it with a new one for around $10. After resetting the vehicle's computer by disconnecting the battery, the check engine light returned after two days. A second visit to AutoZone confirmed the same P0440 code. This strongly suggests that the issue is not with the gas cap. I'm seeking advice on possible underlying causes of this EVAP system failure. Any insights or troubleshooting steps would be greatly appreciated.

Related fault codes
P0440
Comments (4)
Anonymous 2006-10-03 08:23

Check the evaporative vent valve — it may be stuck open or failing to close during EVAP tests. A smoke test can help identify leaks in the system, including those above the fuel tank.

Anonymous 2008-11-17 14:36

I experienced a similar issue and was diagnosed using a smoke machine connected to the EVAP system. The technician found a leak above the fuel tank, which required replacing the evaporative canister at a cost of $570 USD. After running the tank low, the canister was ordered but not delivered — I then refilled the tank, and the check engine light turned off. When I returned to the shop, they claimed the problem still existed despite the light being off. This experience raised serious doubts about their diagnosis. Thanks to The BatteryShop for re-running diagnostics and confirming emissions passed without any repair — it was a relief! — Mike, Warwick, RI

Anonymous 2008-12-05 12:24

In some vehicles, especially older models like the 2001 Pontiac Firebird, the EVAP vent valve can malfunction due to mechanical sticking or improper operation. This often causes the P0440 code to appear and then disappear intermittently as the system resets.

Anonymous 2008-12-07 18:26

depending on how the evap system is made up depending on the vehicle make there are many problems with the vent valve sticking or not closing when the ecm does the evap test. this is why many times a light will come on with a evap code and then will go off for a while.