Blogs Car Info Our Show Deals Mechanics Files Vehicle Donation

Gasket Leak

Ok I just bought a used 2003 Ford Focus from a dealership which I am financing and after the second day driving the check engine light came on. Once I saw that I took it back to the dealer and he told me the sensor was very sensitive and because I didn’t close the gas tank tightly the light came on. I didn’t feel satisfied with this answer so I took the car for a diagnostic. They informed me that the car had a gasket leak. I then took the car back to the dealership and told them what I had been informed and the mechanic told me that it wasn’t a big deal, nothing for me to worry about. Now I don’t know much about cars and I have been doing a little research of my own and a gasket leak seems to be a big problem. Does anyone have any advice on what I should do?

There are lots of gaskets in a car, some are not a big deal and others are a very big deal. Can’t give you an answer about your “gasket leak” without more information.

Thank you. What other questions do I need to ask?

For starters, you should ask the folks who did the diagnostic, “Which gasket has a leak”?
Telling you that your car has “a gasket leak” is about as helpful as a dentist telling you that one of your teeth has a cavity. Specifics are always best.

If the leaking gasket in question is the one on the gas cap, then you have a really cheap solution at hand, as a new gas cap is not expensive. Other gaskets…get out the check book…

Stop at a parts store and have them download and print the "fault codes:. Many will do so free of charge. The codes will look similar to one of the below list. There are literally hundreds of them, so it’s impossible to guess what they’ll be. These are just examples.

Post the codes here and we’ll walk you through the process.

* DTC P0440 Evaporative Emission (EVAP) System
* DTC P0441 Evaporative Emission Control System Incorrect Purge Flow
* DTC P0442 Evaporative Emission (EVAP) System Small Leak Detected
* DTC P0443 EVAP Purge Solenoid Valve 1 Control CKT
* DTC P0444 Evaporative Emission Control System Purge Control Valve Circuit Open
* DTC P0445 Evaporative Emission Control System Purge Control Valve Circuit Shorted
* DTC P0446 EVAP Vent Solenoid Valve Control System
* DTC P0447 Evaporative Emission Control System Vent Control Circuit Open
* DTC P0448 Evaporative Emission Control System Vent Control Circuit Shorted
* DTC P0449 Evaporative Emission (EVAP) Vent Solenoid Control Circuit
* DTC P0450 Fuel Tank Pressure Sensor Circuit
* DTC P0451 Evaporative Emission Control System Pressure Sensor Range/Performance
* DTC P0452 Fuel Tank Pressure Sensor Circuit Low Voltage
* DTC P0453 Fuel Tank Pressure Sensor Circuit High Voltage
* DTC P0454 Evaporative Emission Control System Pressure Sensor


* DTC P0171 Fuel Trim System Lean Bank 1

Good. That means that your fuel mixture has been detected as being too lean. Prime candidates for the cause of that are the oxygen sensor, the injector, or one of the other sensors that factor into fuel metering, such as a mass airflow sensor. It’ll take a shop to determine exactly what needs changing, but the good news is that it’ll be a diagnosable and affordable fix. You have a four cylinder engine (correct me if I’m wrong), so the “bank 1” is really meaningless. They use that circuit on the ECU, so that’s how it presents.

If you have a 30-day or some other form of warranty, print this thread, bring the car back immediately to get the problem on record, and tell them it needs fixing. Then keep your copy of the shop order in case the CEL commes back on again.

Sincere best.

DTC 0171 can also be caused by a vacuum leak, like the intake manifold gasket. That was the solution to my Ford Explorer, which turns out to be a common repair on the 4.0L SOHC engines. A throttle body gasket can also cause this code. My first check is the rubber vacuum line connections, as many cars use nylon line with rubber connectors. The nylon lasts practically forever, but the rubber breaks down and cracks or breaks completely, causing leaks.

The dealership is giving you the run-around, hoping you’d just go away. Do you have a warranty? A car this old is usually sold as-is, but some dealerships offer extended warranties as a selling point. A code P0171 can never be caused by a loose or faulty gas cap, and that is the first tip-off they are being far less than honest.

Excellent ppint, Busted. I forgot about intake manifold gaskets.