1999 Expy 5.4L Code P0452 and P0453
 

In May of this year a few QT gas station in my area sold gas contaminated with diesel. As a result QT had all the cars that received the contaminated gas, including my '99 Expy which I hardly ever drive and happen to get gas that particular day, taken to the Ford Dealership where they did a cleanup of the fuel system to the tune of almost $1,000.

Since then I have driven the Expy about 70 miles and today, when I drove it to pick up a big box, the check engine light came on. I plugged my code reader and it shows code P0452 and P0453. What exactly are these codes and how feasible is that it is related to the contaminated fuel issue? If it is, I would like to think that Ford will fix the issue and bill it to QT, after all, I have driven the truck only 70 miles. If it is important, the temperatures was around 100 degrees today.

If it is not, what is the solution and/or parts? BTW, about a year ago, the fuel pump was replaced but I did not get any codes until now.

Any help you can provide will be greatly appreciated.

These codes can show up if the gas cap isn't on tight or if it isn't sealing good to the filler neck.

With the hot weather we have had it is possible that the cap and/or seals have been affected; however, I would think hot weather would make the seal tighter and cold weather looser.

Those codes have nothing to do with the gas cap.

They are electrical fault codes for the FTP sensor.

So a replacement of the FTP sensor is the potential answer?

Since the P0452 is a code for the Emission System Pressure Sensor/Switch Low input and the P0453 is a code for the Emission System Pressure Sensor/Switch high input as per scanner, does this mean there are two of them? and if this is the case, what are the chances that they are both bad?

Again, is it possible that the sensor(s) was (were) damaged by the contaminated gas?

Where is the sensor(s) located and how easy it is to replace?

Thanks in advance for your help.

P0452 EVAP System Pressure Sensor/Switch Low DTC

Potential causes for this DTC include:
•Failed fuel tank pressure sensor
•Harness to the sensor has an open or short circuit
•Faulty electrical connection to the FTP sensor
•Cracked or broken vapor line to the vacuum canister
•Cracked or broken positive vapor line to the tank
•Plugged line
•Leaky gasket at the fuel pump module
•Gas cap left loose resulting in a loss of vacuum
•Pinched vapor line

Thanks for the info. Sound like it could be a bad line or connection left over from when the fuel system was purged and cleaned. I will call the dealer tomorrow and see what they say.

That's not a Ford-specific code description. As per the SPECIFIC PC/ED for the OP's vehicle, the CORRECT descriptions are as follows:
Gas cap problems are usually P0442, P0455, or P0457 on a '99.

Possibly. There are specific diagnostics to be done to pinpoint the fault. However, when codes that directly contradict each other are present, it's more often the sensor than not.

The FTP sensor is on the top of the fuel tank, I don't know how hard it is to get to or if it will be necessary to drop the tank on your particular truck. It's unlikely the gas caused the problem.

I'm aware of what's what. But I also know that both of these codes deal with excessive pressure or vacuum within the fuel tank. Quite frankly I'd rather tell someone to first check the gas cap instead of telling them to drop the tank in order to access and test the sensor. If it's not the cap they've lost 30 seconds, if it's not the sensor they've lost half a day.

I checked with a friend who is the head of Fleet maintenance for one of the local Counties and he indicated that more often than not it is indeed the gas cap, and since it is a pressurized system, it can cause the error code; they do have a dozen Expeditions in their fleet and it has happened often. He also indicated that they had checked with the manufacturer before and the codes are not an issue performance-wise and they affect mostly the amount of pollution generated; the main problem is that other codes might shop up and you would not know since the check engine light is already on.

In any case, I reset the gas cap, erased the codes and drove the truck about 20 miles and the check engine light has not come back...keeping fingers crossed.
I will post a follow up in a few days.

Got mine crossed for you too! :-X22

I'm always hoping for the simple fix! Taking off and then putting back the gas cap is not too far off the max of my mechanical skills! :-X04

Don't worry, when the time comes we'll walk you through it. :)

I've learned a lot from this forum. I know I can count on you guys to give the info needed to help. :-X10