In this video we will be cover all the necessary testing procedures for trouble code P0452 “EVAP Pressure Sensor Signal Low/Short”. The vehicle in test is a 2002 Chevy Silverado 4.8 but these same procedures can be followed on all General Motors fuel tank pressure sensors as well as every other pressure sensor on the car. Including MAP and BARO sensors.
Engine Performance Diagnostics chapter 8
Symptom
– check engine light with a P0452 code
Fix
– replace faulty fuel tank pressure sensor
Tests shown
– pressure sensor description, operation and testing
– how to perform a signal circuit integrity test (chapter 10)
– voltage measurements of the tank pressure sensor
Tools used
– scan tool
– digital multimeter
– back-probing pins
Playlist
– (Chapter 8) Pressure Sensor Testing, MAP, BARO, DPFE, fuel tank and rail pressure sensors
https://www.youtube.com/playlist?list=PLAFYVCyenqcoFWIaYzFZcB5PX5iOMiDTQ
Related videos
– Power Steering Pressure Sensor Test (P0550) – Toyota
https://youtu.be/WLLxcfC-zeQ
– Ford Ranger EGR Flow Trouble Code P0401 (DPFE fault)
https://youtu.be/RUmH4lwTLKs
– No Start from a shorted MAP sensor (Honda, Acura)
https://youtu.be/za13UnpbH7E
For more information on this topic, I have written a “field manual” called Engine Performance Diagnostics which is available at www.scannerdanner.com as an eBook or paper book.
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Disclaimer:
Due to factors beyond the control of ScannerDanner LLC, it cannot guarantee against unauthorized modifications of this information, or improper use of this information. ScannerDanner LLC assumes no liability for property damage or injury incurred as a result of any of the information contained in this video. ScannerDanner LLC recommends safe practices when working with power tools, automotive lifts, lifting tools, jack stands, electrical equipment, blunt instruments, chemicals, lubricants, or any other tools or equipment seen or implied in this video. Due to factors beyond the control of ScannerDanner LLC, no information contained in this video shall create any express or implied warranty or guarantee of any particular result. Any injury, damage or loss that may result from improper use of these tools, equipment, or the information contained in this video is the sole responsibility of the user and not ScannerDanner LLC.
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What's missing which is very important is where the scanner is plugged in when ref is jumped to signal…..it has to be connected to the PCM?? But where and how?
Very helpful. Thanks!
Is it common for cars such as a ford f150 and ford SUV to use the same voltages to set up a fault or typical run conditions such that you could take one from one of these cars and adapt it with fittings to the other and have the system work? 🙂 My 04 F150 has a inline sensor and is difficult to find( and is expensive as they want to sell you all the fuel lines with it), and the other Fords have a in tank plug in unit that you can find anywhere for cheap! Thanks for your time and expert information.
I know this is an old video, but have you ever seen a P0451 on a Ford Pickup? mine is a 04 5.4l F150 Lariat. I have looked at the sensor and grounded the signal and the voltage went to 0 and took the 5v to signal and got 5v. The voltage changes but I guess not enough. Suggestions on how to proceed?
someone is snoring
The dude snoring was annoying. Back in my high school political science class if someone was sleeping the teacher would kick the metal garbage can across the room & people would jump out of their seat. 🙂
nice tutorial but I had one question, what if the signal line and ground are reading at 4.96v like the 5v and signal line? bad grounding?
2006 Chevy Optra (p0454, then p0452) – this is the same car as Suzuki Forenza/Reno(USA)
Hello Paul,
I have followed your Video instructions and below are the tests i have performed on the FTPS problem so far. I am a DIY'er and seem to have hit a block in the road.
I have no wiring diagram for this cars FTPS circuit as i cannot find
one. I have a service manual for a 2004 Optra and it doesn't list
anything for the FTPS circuit or ECM pin layouts
NOTE: I do not have a Fancy dancy scanner with square waves etc. I only have a simple Actron scanner CP9580a and a DMM and test light.
Here is what i have diagnosed so far:
(( CONNECTOR UNPLUGGED ))
With Key off
——————-
1.) I have continutity on the ground wire(black)
With Key on Engine off
———————————-
2.) 5Volt Reference – tested 4.99V on the reference wire (gray)
3.) Signal Wire – jumped 5Vref to signal and backprobed the signal wire
(ecm side of connector). Test showed 4.99v proving no connector fault.
(( CONNECTOR PLUGGED BACK IN ))
4.) FTPS test – removed FTPS from Fuel Tank Pump assembly and applied
-10kpa vacuum on the sensor and it ranged from 1.3v – 4.74v
After releasing the vacuum pressure voltage returns to 1.3v ,,,,Did test 2 or 3 times to verify.
5.) Purge Valve – removed from car and applied voltage to test valve open close operation while applying vacuum – Valve opens. Also listened to the purge duty cycle with stethascope and valve was rattling away.
6.) Vent valve – removed from car and applied voltage to test valve
open close operation while blowing thru it – Valve closes.
7.) Gas cap is brand new.
8.) The Drive Test Diagnosis – The MIL IS ON !!!……
After resetting MIL and now 93km later the "Evap Drive Cycle Monitor" is
complete and "DTC P0454 is confirmed". P0452 hasn't reappeared as yet,
but rest assured it will as i have done this a few times already over
past year.
With the DMM connected to ground and backprobed to the signal wire on
connector (ecm side) i observed the Voltage reading while driving for 15
minutes. At very low load The signal was perfect (1.4V-3.1V).
Went home let car cool and retested. Drove same distance never tromping
on throttle. Stopped, waited a few minutes and restarted car and the MIL
went off (expected). All the drive time the FTPS signal Voltage was
perfect and MIL went off.
SO I APPLIED SOME FORCE TO HER ON THE NEXT TRIP FLOORING THE GAS PEDAL
WHILE OBSERVING THE DMM VOLTAGE and sure enough the voltage dropped
below threshhold and went haywire at times. This resulted in the MIL
coming back on IMMEDIATELY after the second attempt. I am almost sure
that the code is being set when there is positive pressure in tank,
because freeze frame data indicates PURGE % = 0.
Below .1 Volts i think is the threshhold which has to happen on 2
consecutive trips for the MIL to come back on and my testing confirmed
that.
But i have reservations about going out and replacing the sensor
(throwing money at parts) until am absolutely sure about the fix.
9.) Commanded the Vent valve closed with my scanner and applied .5 psi shop
air from the evap hose before the purge valve. Everthing seemed to hold
pressure but i have no way of determining this as I dont have a fancy
smoke machine with pressure gage). So i attached a balloon to the Vent
Solenoid end of EVAP system and waited 10 minutes. Came back and the
balloon was still holding all pressure, so it seems that i have no
leaks, thus no leak codes….dah!!
PAUL PLEASE ADVISE, AS I AM NOT SURE WHICH FORK IN THE ROAD TO TAKE FOR THE
NEXT STEP. I dont have a wiring diagram showing the FTPS circuit nor do
i have a pin layout of the ECM to do a short / open testing on the REF
& signal wires. You mentioned in your video not to worry about ground wire in this case and it makes sense.
If anyone has the FTPS wiring diagram and ECM pin layout i would be forever grateful as i cannot find them anywhere on the WWW.
Whats really puzzling is that I have a 2004 Optra Service Manual but it doesn't show any information regarding the FTPS.
PS> I LOVE YOUR VIDEOS – YOU ARE THE BEST TEACHER OUT THERE BAR NONE !!! …..well maybe the legend scotty K.
Hoping you'll see this ScannerDanner. I been fighting an P0455 code on my 06 Silverado now for quit some time. I have 'verified' no leaks in the system. Using an SnapOn scan tool the (new) tank vent valve NEVER closes, but, can be closed manually with the scan tool, and I've verified i does seal off. Also the purge valve continually stays open and never closes. It's like the tank sensor is giving the PCM false readings, or there is something wrong with the PCM. The PCM had been changed after my local dealership said it was giving some strange readings. It was replaced with a used (reflashed for my vehicle) PCM. I've tested the tank sensor wiring like you showed here and I get the 5v reading on the scan tool, so I know at least those two wires are good, but, could a bad ground from the PCM be causing my problem. The sensor voltage NEVER changes from a constant steady reading sitting at an idle, or driving on the highway even after trying 2 different tank sensors. one sensor stayed at 1.2 volts, and the other stays at 1.5 volts on the scan tool. 'COULD' it be the blk ground wire back to the computer causing this, or something else? This thing is about to drive me NUTS!!!!! LOL! WHAT could be causing both valves to stay open ALL the time?
Thank you very much for this very detailed video! It helped me understand why I have voltage on the signal leg of my VPS with sensor unplugged.
NOT ONE TAKES ABOUT, Other Reasons Why You Get Po452 code. I have a 2004 Silverado that sat for along time. I removed the fuel pump assembly, empty the tank, wipe clean and reinstalled all. Tried to start engine, it would crank, but hot start. Sprayed starter fuel into intake and it would start then die when starter fuel ran out. When to Auto Zone and paid $140 (Refundable if returned in 90 days) and found I had a P0452 code. I kept thinking it had to do with the opening of the fuel tank. Finely (After watching hours of videos) decided to remove fuel pump system. Cleaned opening and o-ring making sure o-ring was in the slot. After installing fuel system, noticed o-ring had come out, moved back into the groove, installed ring, and all connectors. After cranking 2 times, fired right up. All side remember hearing that if the gas cap was not tight or was leaking can cause the same problem. I wanted to pass along since I did not find a single video taking about the solution of a lose of pressure or a failed gas cap under P0452 code.
p zero Mr Danner LOL
how do I test a pressure sensor, 04 ford escape it has 2 hoses side to side the signal wire