2001 Taurus Gas Cap/Check Engine Light Problem

I have a 2001 Ford Taurus SE that has a problem with the gas cap warning light and check engine light. My wife was driving the car on the freeway and hit a brick or piece of wood and it dented the fuel tank. At first I got the gas cap warning light but the check engine light came on later. I took it to the dealer and they said that there were no leaks and it was OK to drive. However, the gas cap warning light and check engine light is back on again. I took it to Autozone today and the put a code reader on it. They said it is either the gas cap or a vacuum leak. Any ideas on what the problem is and how to fix it? Thanks.

Since this new post is more detailed than your other post which I responded to, I've deleted your other post and pasted my response here. Please don't post the same question in multiple places.

Did you get the full code from Autozone? There are a lot of possibilities, but having the exact code wil help narrow the search.

-Rod

I took the car to Autozone again this morning and had them read the diagnostic codes. They cleared the memory and the gas cap warning light is off. But the check engine warning light came back on immediately. There were two (2) diagnostic codes PO443 and PO174. Let me know if you have any ideas to correct these problems. Thanks.

I don't know the actual codes, shorod can probably help with those, but the gascap and check engine lights kinda sound like it got part of the evap emissions system.

The system is supposed to be able to keep a vacuum or pressure and it might have a hole somewhere.

Per the factory service manual:
P0443 - EVAP Control System Canister Purge Valve Circuit Malfunction. The PCM monitors the EVAP canister purge valve circuit for an electrical failure. The test fails when the signal moves outside the minimum or maximum allowable calibrated parameters for a specified purge duty cycle by PCM command.
VPWR circuit open
EVAP canister purge valve circuit shorted to GND
Damaged EVAP canister purge valve
EVAP canister purge valve circuit open
EVAP canister purge valve circuit shorted to VPWR
Damaged PCMMonitor EVAPPDC PID and voltage between EVAP canister valve signal and PWR GND in output test mode with key ON engine OFF (or in key ON engine RUNNING mode). EVAPPDC PID at 0% and voltage less than 1.0 volts (or EVAPPDC PID at 100% and voltage less than 0.5 volts) indicates a hard fault.

This code could be due to something getting damaged by the road debris. The EVAP canister purge valve is located in the right rear of the engine compartment, but the EVAP canister is located near the fuel tank.

The P0174 - System too Lean (Bank 2) has been addressed on this forum before, so I'll let you try out the handy "Search this forum" tool from the Taurus forum main page to get details on possible causes of that code.

-Rod

Keep in mind that it's possible for one code to be causing the second code so I would focus on code P0443 first, unless the second code is easier to rule out.

I have been researching the P0174 Code which indicates a lean condition only on Bank 2. I get the impression that it may be the O2 sensor since the lean condition is only on one side. Any comments?

I have been researching the P0174 Code which indicates a lean condition only on Bank 2. I get the impression that it may be the O2 sensor since the lean condition is only on one side. Any comments?

You may want to look for a vacuum leak on this code too... Wouldnt be suprised if there is a vacuum leak caused by the road debris.

Mine just came on after getting my car washed last night. It came on about 15 minutes after the wash. Could water have affected the sensor? I checked the gas cap and it's secure and tight. Any ideas?