CODE P0452 READS IN MY SCANNER

[StibbyWonder]

HAPPY NEW YEAR EVERYONE, MY EXPED BUDDIES!

Hi, I would like to ask if you encounter this code P0452 that reads in my scanner and says EVAP (Evaporative Emission System) Switch A Circuit Low, based on my initial research, this codes has a lot to checked and I checked only the gas cap sealed, it is still sealed and fine. Next is I removed the TPS since the live data is not meeting with the correct voltage when I reached the stages of RPM, 2,500 to 3,500 RPM. How was your experience in repairing/removing this code?

Also may I know if this TPS is still the original TPS for 2nd Gen Expedition? (see photo below)



Looking forward to your answers/experiences on how to handle this code.


Thank you everyone much love!

 

[Hamfisted]

I looks like an original Motorcraft part, and the correct part number. If it's original to that particular vehicle, you wouldn't know unless you were the original owner and had all the service records. If this is the first time getting the P0452 code, try cleaning the gas cap mating surfaces and make sure the cap is on tight, then clear the code and see if it comes back. We usually see that code after someone refills their gas tank and fails to tighten the gas cap, or leaves the engine running while they fill the gas tank.





Throttle Position Sensors at Rock Auto






.

 

[StibbyWonder]

I looks like an original Motorcraft part, and the correct part number. If it's original to that particular vehicle, you wouldn't know unless you were the original owner and had all the service records. If this is the first time getting the P0452 code, try cleaning the gas cap mating surfaces and make sure the cap is on tight, then clear the code and see if it comes back. We usually see that code after someone refills their gas tank and fails to tighten the gas cap, or leaves the engine running while they fill the gas tank.


View attachment 86423


Throttle Position Sensors at Rock Auto






.

Oh I see seems like this is the original part. Okay I'll try to work on what you advice. I'm a second owner. Thank you!

 

[Broncoholic]

2003 Expedition gas tank is notorious for small cracks at the vent fittings. That is likely causing your low pressure/vacuum leak. Do you ever smell gas if you park shortly after filling your tank full? If so, that's an indicator of gas seeping out of a vent fitting crack.

 

[texasscot]

If the code is related to a small vac leak like a gas cap would give you may have cracks in the cream-colored two plastic vent ports on top of the tank at each end. Lots of info on this. Here's one video. https://www.youtube.com/watch?v=G6Zz1zoiq_4.
I wouldn't recommend JB weld as it doesn't last. I know because i did it. Plastic welding is the way to go. You could smoke test to check it out.
(edit to add; i hadn't seen broncoholic's post as i was typing when it came in lol)

 

[StibbyWonder]

Hey guys I know it's been more than a month since I replied. I just want to give you an update, I already replaced the Throttle Position Sensor (TPS) and the Fuel Filter, now the problem is it won't start. It seems like the failure is in the fuel pump? I also bought a gas cap just to replace my old one and it's shipped to my house.

I am thinking, and searching online it seems like my fuel pump is weak? May I know your advices on how to safely put down these big fuel tank? I am planning to replace the fuel pump.

 

[Broncoholic]

Don't jump to replacing a fuel pump without diagnostics. It's a waste of time and money. Turn the key to On and listen for the pump to turn on and prime for a second. If you hear it, then you know you have power and the pump is running. Go borrow a fuel pressure gauge from an auto parts store like Autozone and check the fuel pressure. If you have pressure then it's not the fuel pump - time and money saved. If you don't hear it, then the pump is bad or you're not getting power to the pump. 2003/2004 Expedition is notorious for the fuel pump relay burning out on the fuse panel circuit board. The common symptom is the engine stops while running and won't restart for 5 or 10 minutes, not a no-start condition that you're experiencing, but anything is possible. If the relay is bad, then the pump is likely good - time and money saved.

 

[StibbyWonder]

Don't jump to replacing a fuel pump without diagnostics. It's a waste of time and money. Turn the key to On and listen for the pump to turn on and prime for a second. If you hear it, then you know you have power and the pump is running. Go borrow a fuel pressure gauge from an auto parts store like Autozone and check the fuel pressure. If you have pressure then it's not the fuel pump - time and money saved. If you don't hear it, then the pump is bad or you're not getting power to the pump. 2003/2004 Expedition is notorious for the fuel pump relay burning out on the fuse panel circuit board. The common symptom is the engine stops while running and won't restart for 5 or 10 minutes, not a no-start condition that you're experiencing, but anything is possible. If the relay is bad, then the pump is likely good - time and money saved.

I actually tried to test if the pump is working, I put my phone on video underneath my vehicle and I heard there is the humming sound when I put ON accessory mode the vehicle. I tried also to open one line from the fuel filter if the fuel will come out and it did came out.

I am not sure though if the pressure were correct and I don't have any means to check the pressure aside from I have a scanner, can a scanner check it's live data even though the car is not engine turned on? Only key on but in accessory mode?

I appreciate your inputs.

 

[Hamfisted]

Test for fuel pressure at the fuel rail schrader valve with the key ON. If you don't have a fuel pressure test gauge, even a tire gauge will work to show you how much fuel pressure is reaching the fuel rail. You should see 45-55 psi with the key on, engine not running. The schrader valve is on the passenger side of the fuel rail.







.

 

[Broncoholic]

I actually tried to test if the pump is working, I put my phone on video underneath my vehicle and I heard there is the humming sound when I put ON accessory mode the vehicle. I tried also to open one line from the fuel filter if the fuel will come out and it did came out.

I am not sure though if the pressure were correct and I don't have any means to check the pressure aside from I have a scanner, can a scanner check it's live data even though the car is not engine turned on? Only key on but in accessory mode?

I appreciate your inputs.

The fuel pump runs and pumps - the probability that it's good is much higher than it's bad. Find a way to test the pressure.

If you're 100% decided on replacing the fuel pump, then you need to drain the tank as much a possible to make it light. I removed my tank by myself with a floor jack once it was near empty.

Good luck.

 

[StibbyWonder]

Test for fuel pressure at the fuel rail schrader valve with the key ON. If you don't have a fuel pressure test gauge, even a tire gauge will work to show you how much fuel pressure is reaching the fuel rail. You should see 45-55 psi with the key on, engine not running. The schrader valve is on the passenger side of the fuel rail.



View attachment 86732



.

Okay, I will try this today and will give an update. Thank you.

Also just to add, I checked this fuses and relay, see photo below.


This one I just checked first physically and it seems fine and there's no burnt smell but I will get my tester to test this relay.


This one also I pull out and the fuse is still connected.



This one however I cannot check because it is fixed to the fuse board.

 

[Broncoholic]

Okay, I will try this today and will give an update. Thank you.

Also just to add, I checked this fuses and relay, see photo below.

View attachment 86734
This one I just checked first physically and it seems fine and there's no burnt smell but I will get my tester to test this relay.

View attachment 86735
This one also I pull out and the fuse is still connected.


View attachment 86736
This one however I cannot check because it is fixed to the fuse board.

Yes, R303 is the relay that burns out or melts the solder on the board. That is the problem I was talking about. I had to replace my R303 relay 10 years ago (3/20/2016). Your pump is running, so fuses and relays are not the problem.

 

[whtbronco]

If you need to take the tank out here's what I did to get mine out. Thus far it doesn't sound like tank removal is warranted though.

I had ~24 gallons of fuel in my tank and with the fuel pump failed I could not drain the tank. So I used my floor jack with my cross beam replacing the standard jack pad. I then removed the rubber pads and screwed an 18" long 2x4 to each end. This provided really good support for the heavy tank and made it fairly safe.

I also had my Expedition's tires sitting on 9" tall wooden ramps which provided the needed clearance.

Steel Floor Jack Cross Beam

Amazing deals on this Steel Service Jack Cross Beam at Harbor Freight. Quality tools & low prices.

www.harborfreight.com

 

[StibbyWonder]

Yes, R303 is the relay that burns out or melts the solder on the board. That is the problem I was talking about. I had to replace my R303 relay 10 years ago (3/20/2016). Your pump is running, so fuses and relays are not the problem.

I just did the test but it seems like the fuel is not reaching the engine I poke the shrader valve as per advise of Hamfisted, and there is no fuel came out. I prime the key multiple times and keep it in ON position and still there is no fuel coming out of the valve.

I scan it using my scanner in key ON only and here is the result/s:


These two photos above are the before I turned on the key in ON/accessory position.




These two photos above are the result/s after I turned ON/accessory the key. So in my scanner it is in Key ON, engine OFF mode and here are the live datas. Also, there is no error found out. I am just curious why is the Fuel Pump and Fuel Pump Monitor is still in OFF?

Thank you for your advices.

 

[whtbronco]

Well the PCM thinks the fuel pump is not running. Are you certain you can hear the pump running when you turn the key to ON? No pressure at the fuel rail Schrader valve and the scanner showing the pump is off seems to indicate the pump is not running.

I know when my fuel pump relay, R303, first failed the pump did still run after waiting a couple minutes for the relay to cool down. I was able to smell the failed relay, but there was no visible sign it had melted until it was removed. I disassembled the central junction box and removed the relay with a soldering iron and solder sucker.

A while later when my fuel pump failed it did run, but sounded strange for 4 or 5 cycles. On day 3 at the last planned start it totally failed and no longer developed pressure so the engine couldn't start.

Can your scanner turn on the fuel pump? Some scanners can send commands, some cannot.

You can also turn the ignition to ON and check the wires coming out of the fuel pump relay for power to help isolate the relay or the pump.

 

[StibbyWonder]

Well the PCM thinks the fuel pump is not running. Are you certain you can hear the pump running when you turn the key to ON? No pressure at the fuel rail Schrader valve and the scanner showing the pump is off seems to indicate the pump is not running.

I know when my fuel pump relay, R303, first failed the pump did still run after waiting a couple minutes for the relay to cool down. I was able to smell the failed relay, but there was no visible sign it had melted until it was removed. I disassembled the central junction box and removed the relay with a soldering iron and solder sucker.

A while later when my fuel pump failed it did run, but sounded strange for 4 or 5 cycles. On day 3 at the last planned start it totally failed and no longer developed pressure so the engine couldn't start.

Can your scanner turn on the fuel pump? Some scanners can send commands, some cannot.

You can also turn the ignition to ON and check the wires coming out of the fuel pump relay for power to help isolate the relay or the pump.

Hi,

I tried to turn ON and OFF the key for 5 times, I even remove one line from the fuel filter, and there's the fuel coming out but I am not sure if the fuel pressure is enough to reach the engine.

So far there's no burnt smell to the fuse box, tried to interchange the relays but seems like relays are good.

My scanner cannot send command.

I already bought online the fuel pump assembly, I will changed it. It is good too since the car never changed the fuel pump for more than 20+ years and from there we will see who is the real culprit.

I will update on this thread after I changed the pump, wish me luck guys! Thank you all for our inputs and it helped me a lot.

 

[whtbronco]

Changing the pump doesn't sound like an unreasonable path forward based on what you are seeing. Good luck, it's not an easy task mostly because the tank is large and reaching the connections on top can be a bit of a challenge. Removing the spare tire will help make access to the fuel filler neck and rear vent easier.

The quick release connectors have o-rings in them. If the o-rings still look to be in good shape then just rub a bit of motor oil on them with your finger before reassembly. This will help ensure they don't tear when you push the connectors back on.

I see you recently changed the fuel filter, that's good since it should be changed when the pump fails.

 

[StibbyWonder]

Changing the pump doesn't sound like an unreasonable path forward based on what you are seeing. Good luck, it's not an easy task mostly because the tank is large and reaching the connections on top can be a bit of a challenge. Removing the spare tire will help make access to the fuel filler neck and rear vent easier.

The quick release connectors have o-rings in them. If the o-rings still look to be in good shape then just rub a bit of motor oil on them with your finger before reassembly. This will help ensure they don't tear when you push the connectors back on.

I see you recently changed the fuel filter, that's good since it should be changed when the pump fails.

Hi, sorry it's been a while I did the testing of the fuse box assembly, and fuse relays in my Ford. The reading in the multimeter when I put in DC and connect the positive to the pin where the green and yellow wire socket normally connected, it reads 6.6V and in my research it should be 12V. See photo below.


Also, I test the fuses and relays everything is in order and working properly so my guess is the R303 issue maybe it is burnt?

Also I tried to bypass and connect directly into my positive battery terminal going into the green/yellow wire and my car turned on.

Any suggestions or do you think I need to replace the whole fuse box assembly since R303 cannot be pulled out like the other relays.

Thank you so much!

 

[Broncoholic]

If you're good with a soldering iron, you can replace the relay and save a lot of money. You need a solder sucker tool to remove the solder once you heat it. You should be able to buy the tool and new relay for 1/10th of the cost of a new fuse box assembly. Take your time when disassembling the box. I used a piece of cardboard to transfer my fuses over to so I knew their position. Take note of orientation of the small metal clips inside; it's possible to install them backwards. I replaced my relay 10 years ago (3/20/2016).

 

[StibbyWonder]

Thank you for your advice, I have to remove the whole fuse assembly first. Solder tools I think it is available in my place. Thank you for your advice, appreciate it.