Fuel code P0460 won’t pass smog

Petericaza

Member
Dec 3, 2019
66
2
8
48
San jose
Hi I recently bought my v6 swapped to v8 4.6 l mustang and I now have a p0460 code popping up which is keeping me from passing smog. Not sure how it’s up because I was at a 1/4 tank and I went for a fill up put about 10 gallons in and it read full. Later that week I started the car and a CEL came on P0460 I’m pretty pissed rn about this. Can anyone help??
 
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wmburns

SN Certified Technician
Aug 14, 2009
5,676
471
164
Houston Texas
Anytime a DTC code calls out a circuit malfunction it means there is something sooooooooo wrong with the electrical part of the circuit that the PCM can't perform any diagnosis. Think wiring fault or bad sensor.

Do you have an ODB2 scanner? If you did have the ability to monitor the fuel level (FLI) PID it might make short work of trouble shooting this.

Also note that the key to understanding this is NOT to focus on what the cluster fuel level gauge says. It is only reflecting what the PCM is "telling" it to display. The key is to see exactly what the FLI volts are doing. Does it "drop out"? Is it changing rapidly? Is it too high/low?

Without an ODB2 scanner it may be possible to use the Cluster diagnostic mode to monitor the FLI PID. But this may not help with a voltage return that is way outside of what the PCM is expecting.

Cluster diagnostic mode:

*note, given the amount of help you have been previously been given on other threads it might be useful to others to update the other open threads with "lessons learned".

>>From Ford service manual
P0460 - Fuel Level Sensor Circuit Malfunction
The PCM monitors the fuel level input (FLI) circuit for electrical failure. The test fails when the signal moves outside the minimum or maximum allowable calibrated parameters for a specified fuel fill percentage in the fuel tank.​
  • Empty fuel tank
  • Fuel pump (FP) module stuck open
  • Incorrectly installed fuel gauge
  • Damaged instrument cluster
  • CASE GND circuit open
  • FLI shorted to VPWR
  • Damaged PCM
  • Overfilled fuel tank
  • Fuel pump (FP) module stuck closed
  • Damaged fuel gauge
  • FLI circuit open
  • FLI circuit shorted to CASE GND or PWR GND
  • CSE GND shorted to VPWR
Monitor FLI PID and FLI V PID in key ON engine RUNNING. FLI PID at 25% fill (with non matching fuel gauge) and FLI V PID less than 0.90 volts [for FLI PID at 75% fill (with non matching fuel gauge) and FLI V PID greater than 2.45 volts] indicates a hard fault.​
 
Last edited:

Petericaza

Member
Dec 3, 2019
66
2
8
48
San jose
Anytime a DTC code calls out a circuit malfunction it means there is something sooooooooo wrong with the electrical part of the circuit that the PCM can't perform any diagnosis. Think wiring fault or bad sensor.

Do you have an ODB2 scanner? If you did have the ability to monitor the fuel level (FLI) PID it might make short work of trouble shooting this.

Also note that the key to understanding this is NOT to focus on what the cluster fuel level gauge says. It is only reflecting what the PCM is "telling" it to display. The key is to see exactly what the FLI volts are doing. Does it "drop out"? Is it changing rapidly? Is it too high/low?

Without an ODB2 scanner it may be possible to use the Cluster diagnostic mode to monitor the FLI PID. But this may not help with a voltage return that is way outside of what the PCM is expecting.

Cluster diagnostic mode:

>>From Ford service manual
P0460 - Fuel Level Sensor Circuit Malfunction
The PCM monitors the fuel level input (FLI) circuit for electrical failure. The test fails when the signal moves outside the minimum or maximum allowable calibrated parameters for a specified fuel fill percentage in the fuel tank.​
  • Empty fuel tank
  • Fuel pump (FP) module stuck open
  • Incorrectly installed fuel gauge
  • Damaged instrument cluster
  • CASE GND circuit open
  • FLI shorted to VPWR
  • Damaged PCM
  • Overfilled fuel tank
  • Fuel pump (FP) module stuck closed
  • Damaged fuel gauge
  • FLI circuit open
  • FLI circuit shorted to CASE GND or PWR GND
  • CSE GND shorted to VPWR
Monitor FLI PID and FLI V PID in key ON engine RUNNING. FLI PID at 25% fill (with non matching fuel gauge) and FLI V PID less than 0.90 volts [for FLI PID at 75% fill (with non matching fuel gauge) and FLI V PID greater than 2.45 volts] indicates a hard fault.

*note, given the amount of help you have been given on the forums it might be useful to others to update the other open threads with "lessons learned".​
Thanks I’m fairly new to this stuff but would I be able to find this FLI on my obd 2 or do I need a gauge and disconnect the wiring that goes to the pump and check the voltage that way? That last bit from the service manual did not make too much sense to be honest..
 

Petericaza

Member
Dec 3, 2019
66
2
8
48
San jose
Anytime a DTC code calls out a circuit malfunction it means there is something sooooooooo wrong with the electrical part of the circuit that the PCM can't perform any diagnosis. Think wiring fault or bad sensor.

Do you have an ODB2 scanner? If you did have the ability to monitor the fuel level (FLI) PID it might make short work of trouble shooting this.

Also note that the key to understanding this is NOT to focus on what the cluster fuel level gauge says. It is only reflecting what the PCM is "telling" it to display. The key is to see exactly what the FLI volts are doing. Does it "drop out"? Is it changing rapidly? Is it too high/low?

Without an ODB2 scanner it may be possible to use the Cluster diagnostic mode to monitor the FLI PID. But this may not help with a voltage return that is way outside of what the PCM is expecting.

Cluster diagnostic mode:

*note, given the amount of help you have been previously been given on other threads it might be useful to others to update the other open threads with "lessons learned".

>>From Ford service manual
P0460 - Fuel Level Sensor Circuit Malfunction
The PCM monitors the fuel level input (FLI) circuit for electrical failure. The test fails when the signal moves outside the minimum or maximum allowable calibrated parameters for a specified fuel fill percentage in the fuel tank.​
  • Empty fuel tank
  • Fuel pump (FP) module stuck open
  • Incorrectly installed fuel gauge
  • Damaged instrument cluster
  • CASE GND circuit open
  • FLI shorted to VPWR
  • Damaged PCM
  • Overfilled fuel tank
  • Fuel pump (FP) module stuck closed
  • Damaged fuel gauge
  • FLI circuit open
  • FLI circuit shorted to CASE GND or PWR GND
  • CSE GND shorted to VPWR
Monitor FLI PID and FLI V PID in key ON engine RUNNING. FLI PID at 25% fill (with non matching fuel gauge) and FLI V PID less than 0.90 volts [for FLI PID at 75% fill (with non matching fuel gauge) and FLI V PID greater than 2.45 volts] indicates a hard fault.​
Also I did the gauge check the fuel level read 222 but I read that it’s only supposed to display 215 for a full tank.
 

wmburns

SN Certified Technician
Aug 14, 2009
5,676
471
164
Houston Texas
Thanks I’m fairly new to this stuff but would I be able to find this FLI on my obd 2 or do I need a gauge and disconnect the wiring that goes to the pump and check the voltage that way? That last bit from the service manual did not make too much sense to be honest..
With regards to finding the PID on your ODB2 scanner that depends. Likely if a generic ODB2 scanner the answer is no. YMMV In general it will take an advanced ODB2 scanner with manufacturer specific (Ford) support.

So you could do it with a full function ODB2 scanner or do it the "hard way" by disconnecting or probing the wires. Your choice.
 

Petericaza

Member
Dec 3, 2019
66
2
8
48
San jose
With regards to finding the PID on your ODB2 scanner that depends. Likely if a generic ODB2 scanner the answer is no. In general it will take an advanced ODB2 scanner with manufacturer specific (Ford) support.

So you could do it with a full function ODB2 scanner or do it the "hard way" by disconnecting or probing the wires. Your choice.
Would I be able to rent one of these scanners from an autozone?
 

wmburns

SN Certified Technician
Aug 14, 2009
5,676
471
164
Houston Texas
Would I be able to rent one of these scanners from an autozone?
do you have $30?

ForScan ODB2 scanner w ELM327 USB

Or do your research and buy one for yourself. Just bear in mind that you will need a higher end unit than a minimum function generic ODB2 unit.
 

Petericaza

Member
Dec 3, 2019
66
2
8
48
San jose
do you have $30?

ForScan ODB2 scanner w ELM327 USB

Or do your research and buy one for yourself. Just bear in mind that you will need a higher end unit than a minimum function generic ODB2 unit.
Yea I do have 30$ And I’m saving for a good scanner at the moment. But when I rent the tool I look for the FLI level to be hay wire? Also is there a guide to probe the wires in case I don’t make it to my autozone it’s pretty far from where I am
 

wmburns

SN Certified Technician
Aug 14, 2009
5,676
471
164
Houston Texas
Check out www.alldatadiy.com for a full set of Ford service manuals with factory wiring diagrams.

I have an alldatadiy subscription for all of my cars (Ford's and GM's). I'm a big believer in the words of Sun Tzu, "Know your enemy". To me, to know your enemy is to have a much reliable information about your car. Data that I am personally more than willing to pay for as it helps a great deal.



The $30 USB dongle with the ForScan software will do the same job as a scanner costing 100's (or even 1,000's) more.
 
Last edited:

Petericaza

Member
Dec 3, 2019
66
2
8
48
San jose
Check out www.alldatadiy.com for a full set of Ford service manuals with factory wiring diagrams.

I have an alldatadiy subscription for all of my cars (Ford's and GM's). I'm a big believer in the words of Sun Tzu, "Know your enemy". To me, to know your enemy is to have a much reliable information about your car. Data that I am personally more than willing to pay for as it helps a great deal.



The $30 USB dongle with the ForScan software will do the same job as a scanner costing 100's (or even 1,000's) more.
Haha good one will be investing in one of those devices however driving around I noticed my fuel gauge was going down but I’m wondering why that is if according to my sender there’s a “problem” could this code be cause by me starting the car for like 10 seconds quite a few sometimes a week ?? Or that my speed sensor is unbolted?
 

Petericaza

Member
Dec 3, 2019
66
2
8
48
San jose
Check out www.alldatadiy.com for a full set of Ford service manuals with factory wiring diagrams.

I have an alldatadiy subscription for all of my cars (Ford's and GM's). I'm a big believer in the words of Sun Tzu, "Know your enemy". To me, to know your enemy is to have a much reliable information about your car. Data that I am personally more than willing to pay for as it helps a great deal.



The $30 USB dongle with the ForScan software will do the same job as a scanner costing 100's (or even 1,000's) more.
Check out www.alldatadiy.com for a full set of Ford service manuals with factory wiring diagrams.

I have an alldatadiy subscription for all of my cars (Ford's and GM's). I'm a big believer in the words of Sun Tzu, "Know your enemy". To me, to know your enemy is to have a much reliable information about your car. Data that I am personally more than willing to pay for as it helps a great deal.



The $30 USB dongle with the ForScan software will do the same job as a scanner costing 100's (or even 1,000's) more.
also ran a gauge cluster check on the fuel and it was going all over the place
View: https://youtu.be/KRoG_XGsLDM
here is this normal?