How JustAnswer Works:

  • Ask an Expert
    Experts are full of valuable knowledge and are ready to help with any question. Credentials confirmed by a Fortune 500 verification firm.
  • Get a Professional Answer
    Via email, text message, or notification as you wait on our site.
    Ask follow up questions if you need to.
  • 100% Satisfaction Guarantee
    Rate the answer you receive.

Ask Tim's Auto Repair Your Own Question

Tim's Auto Repair
Tim's Auto Repair, mechanic
Category: Chevy
Satisfied Customers: 13070
Experience:  Have owned a repair shop for 25 yrs.
14541291
Type Your Chevy Question Here...
Tim's Auto Repair is online now
A new question is answered every 9 seconds

2001 CHEVY S10: 2 CODES #1 IS PO440 & #2 IS PO452 NO ONE CAN TELL ME

Resolved Question:

HI THERE I HAVE A 2001 CHEVY S10 P/U & IT HAS 2 CODES #1 IS PO440 & #2 IS PO452 NO ONE CAN TELL ME WHAT PARTS TO CHANGE TO CORRECT THIS PROBLEM .CAN ANY ONE HELP PLEASE .THANK YOU MUCH TONY
Submitted: 3 years ago.
Category: Chevy
Expert:  Tim's Auto Repair replied 3 years ago.

hi

these are evap codes..sense you have changed the fuel pump.you may have left a vent hose loose or it is damaged..the 452 code makes me think you may need to clean the wire plug to the pcm[computer],they may be corroded..please print and use the charts below to help you find the problem

thanks

 

Please ACCEPT my answer so I can get credit for my work.i don't receive commission unless you do ..I'm not always going to be giving you good news,so please don't let this stand in the way of you accepting my answer.it does not cost you more money.we will still be able to communicate.. Bonuses and positive feedback are appreciated!if you are not satisfied with my answer,please do not leave bad feed back,i will gladly opt out and let another expert handle the question.if i have sent any diagrams,please print them.they will only stay on here for an hour or so.PLEASE ASK IF YOU NEED MORE HELP

 

P0440

 

Schematic

CIRCUIT DESCRIPTION
The evaporative system includes the following components:

 

  • The fuel tank
  • The EVAP vent solenoid
  • The fuel tank pressure sensor
  • The fuel pipes and hoses The vapor lines
  • The fuel cap
  • The evaporative emission canister
  • The purge lines
  • The EVAP purge solenoid

The evaporative leak detection diagnostic strategy is based on applying a vacuum to the EVAP system and monitoring the vacuum decay rate. The Vehicle Control Module (VCM) monitors the vacuum level via the fuel tank pressure sensor input. At an appropriate time, the EVAP purge solenoid and the EVAP vent solenoid turn ON, allowing the engine vacuum to draw a small vacuum on the entire evaporative emission system. If a sufficient vacuum level cannot be achieved, a large leak or an EVAP system malfunction is indicated. The following conditions can cause this problem:

  • A disconnected or malfunctioning fuel tank pressure sensor
  • A missing, malfunctioning, improperly installed, or loose fuel cap
  • A disconnected, damaged, pinched, or blocked EVAP purge line
  • A disconnected or damaged EVAP vent hose
  • A disconnected, damaged, pinched, or blocked fuel tank vapor line
  • A disconnected or malfunctioning EVAP purge solenoid
  • A disconnected or malfunctioning EVAP vent solenoid
  • An open ignition feed circuit to the EVAP vent or purge solenoid
  • A damaged EVAP canister
  • A leaking fuel sender assembly O-ring
  • A leaking fuel tank or fuel filler neck

Any of the above conditions can set a DTC P0440.

CONDITIONS FOR RUNNING THE DTC

  • No active MAP sensor DTCs
  • No active TP sensor DTCs
  • No active VS sensor DTCs
  • No active O2 sensor DTCs
  • No active ECT sensor DTCs
  • No active IAT sensor DTCs
  • DTC P0125 not active
  • The system voltage is between 10-17 volts
  • The fuel level is between 12.5-87 percent .
  • The ECT is between 4°C-30°C (39°F-86°F)
  • The IAT is between 4°C-30°C (39°F-86°F)
  • The cold start temperature difference (ECT minus IAT) is less than 1.5°C when the IAT is more than the ECT or 8°C when the ECT is more than the IAT
  • The BARO is more than 73 kPa

CONDITIONS FOR SETTING THE DTC
The EVAP system is unable to generate a vacuum more than a calibrated value over a specified period of time.

ACTION TAKEN WHEN THE DTC SETS

  • This is a type A DTC that behaves like a B type, in which the VCM illuminates the MIL after the second key cycle.
  • The VCM stores the conditions that were present when the DTC sets as a Freeze Frame/Failure Records data.

CONDITIONS FOR CLEARING THE MIL OR DTC

  • The control module turns OFF the MIL afterXXXXXtrips when the test has run and passed.
  • A history DTC will clear if no fault conditions have been detected for 40 warm-up cycles. A warm-up cycle occurs when the coolant temperature has risen 22°C (40°F) from the startup coolant temperature and the engine coolant reaches a temperature that is more than 70°C (158°F) during the same ignition cycle.
  • Use a scan tool in order to clear the DTCs.

DIAGNOSTIC AIDS

IMPORTANT: An accurate indication of fuel level is required for the VCM to properly pass or fail this DTC. Always diagnose fuel level sensor DTCs before performing this DTCs diagnostic table. Always check for fuel level sensor DTCs stored in history.

Check for the following conditions:

  • A loose, missing, damaged, incorrect or improperly installed fuel cap
  • Missing or damaged O-rings at EVAP canister fuel vapor and purge line fittings
  • A cracked or punctured EVAP canister
  • A damaged or disconnected EVAP purge line, vent hose or fuel tank vapor line
  • Incorrectly routed or damaged EVAP system purge and vapor lines
  • A poor connection at the VCM. Inspect the harness connectors for the following conditions:
  • Backed out terminals
  • Improper mating
  • Broken locks
  • Improperly formed or damaged terminals
  • poor terminal to wire connection
  • A damaged harness - Inspect the wiring harness to the EVAP vent solenoid, EVAP purge solenoid and the fuel tank pressure sensor for an intermittent, open or short circuit.
  • A kinked, pinched or plugged EVAP purge or fuel tank vapor line - Verify that the lines are not restricted.

Refer to Evaporative Emission (EVAP) System Cleaning before starting repairs. Reviewing the Failure Records vehicle mileage since the diagnostic test last failed may help determine how often the condition that caused the DTC to be set occurs. This may assist in diagnosing the condition.

Diagnostic Chart (Part 1 Of 4)
Diagnostic Chart (Part 2 Of 4)
Diagnostic Chart (Part 3 Of 4)
Diagnostic Chart (Part 4 Of 4)

TEST DESCRIPTION
The numbers below refer to the step numbers on the diagnostic table.

 

  1. Inspect the service port. Make sure that the valve core is not damaged. If the service port is suspect of leakage use the following procedure: Disconnect the purge line from the EVAP purge solenoid valve. Connect a hand vacuum pump to the service port by placing the hose/adaptor over the unthreaded end portion of the service port. Apply vacuum to 5 inches Hg. If the vacuum does not hold replace the entire purge line which contains the service port.
  2. If the vehicle passes the Service Bay Test then an intermittent leak or restriction had occurred. Check the fuel tank cap for a possible loose or OFF condition that may have caused this DTC to set. If the Service Bay Test can not be run, proceed to step 5. If a fault is not currently present the diagnostic table steps will return you to step 3.
  1. Refer to the information supplied with the EVAP pressure/purge diagnostic cart on proper setup and adjustment procedures.
  2. With pressure applied it may be necessary to disconnect the EVAP lines at the components to verify that a line or component is not restricted. A restriction would prevent a vacuum (or the step 9 test pressure) from forming in the fuel tank.
  1. An EVAP pressure sensor that does not correctly respond to vacuum (or pressure) will cause this DTC to set. The EVAP pressure sensor monitors a range from 7.5 inches H2O of pressure to -17.5 inch H2O of pressure (vacuum).

 

P0452

 

Schematic

CIRCUIT DESCRIPTION
The fuel tank pressure sensor responds to changes in the fuel tank pressure or vacuum. This information is used in order to detect vacuum decay or an excessive vacuum during the EVAP diagnostic routing. The fuel tank pressure sensor signal voltage to the VCM varies from a minimum OF about 0.1 volts with pressure in the fuel tank to above 4.0 volts with a high vacuum in the fuel tank.

The fuel tank pressure sensor display on the scan tool has an auto zero feature which occurs at each ignition cycle and is corrected according to the barometric pressure. Because of this, the fuel tank pressure sensor display may not accurately reflect the actual output of the sensor or the conditions within the fuel tank.

The fuel tank pressure sensor diagnosis table is intended to isolate and diagnose the electrical problems with the sensor wiring or the sensor.

CONDITIONS FOR RUNNING THE DTC
The ignition switch is in the RUN position.

CONDITIONS FOR SETTING THE DTC
The fuel tank pressure sensor voltage is less than 0.1 volt for more than 5 seconds .

ACTION TAKEN WHEN THE DTC SETS
The VCM turns ON the MIL after 2 consecutive driving cycles with the fault active.

CONDITIONS FOR CLEARING THE MIL OR DTC

 

  • The control module turns OFF the MIL afterXXXXXtrips when the test has run and passed.
  • A history DTC will clear if no fault conditions have been detected for 40 warm-up cycles. A warm-up cycle occurs when the coolant temperature has risen 22°C (40°F) from the startup coolant temperature and the engine coolant reaches a temperature that is more than 70°C (158°F) during the same ignition cycle.
  • Use a scan tool in order to clear the DTCs.

DIAGNOSTIC AIDS

  1. Inspect the control module harness connectors for the following conditions:
    • Improper mating
    • Broken locks
    • Improperly formed
    • Damaged terminals
  1. Inspect the wiring harness for damage. If the harness appears to be OK, observe the fuel tank pressure sensor display on the scan tool while moving the connectors and the wiring harnesses related to the sensor. A change in the display will indicate the location of the fault. Refer to Wiring Repairs in Diagrams.

 

Diagnostic Chart (Part 1 Of 2)
Diagnostic Chart (Part 2 Of 2)

TEST DESCRIPTION
The numbers below refer to the step numbers on the diagnostic table.

 

  1. If the VCM recognizes the high signal voltage, the VCM and the wiring are okay.

Please ACCEPT my answer so I can get credit for my work.i don't receive commission unless you do ..I'm not always going to be giving you good news,so please don't let this stand in the way of you accepting my answer.it does not cost you more money.we will still be able to communicate.. Bonuses and positive feedback are appreciated!if you are not satisfied with my answer,please do not leave bad feed back,i will gladly opt out and let another expert handle the question.if i have sent any diagrams,please print them.they will only stay on here for an hour or so.PLEASE ASK IF YOU NEED MORE HELP

Tim's Auto Repair, mechanic
Category: Chevy
Satisfied Customers: 13070
Experience: Have owned a repair shop for 25 yrs.
Tim's Auto Repair and 8 other Chevy Specialists are ready to help you

JustAnswer in the News:

 
 
 
Ask-a-doc Web sites: If you've got a quick question, you can try to get an answer from sites that say they have various specialists on hand to give quick answers... Justanswer.com.
JustAnswer.com...has seen a spike since October in legal questions from readers about layoffs, unemployment and severance.
Web sites like justanswer.com/legal
...leave nothing to chance.
Traffic on JustAnswer rose 14 percent...and had nearly 400,000 page views in 30 days...inquiries related to stress, high blood pressure, drinking and heart pain jumped 33 percent.
Tory Johnson, GMA Workplace Contributor, discusses work-from-home jobs, such as JustAnswer in which verified Experts answer people’s questions.
I will tell you that...the things you have to go through to be an Expert are quite rigorous.
 
 
 

What Customers are Saying:

 
 
 
  • I was having a terrible problem with the wheel bearings on my 98 Chevy Cavalier and I suspect that using this website saved me plenty of time and money. Todd L Rochester NY
< Last | Next >
  • I was having a terrible problem with the wheel bearings on my 98 Chevy Cavalier and I suspect that using this website saved me plenty of time and money. Todd L Rochester NY
  • Wonderful service, prompt, efficient, and accurate. Couldn't have asked for more. I cannot thank you enough for your help. Mary C. Freshfield, Liverpool, UK
  • This expert is wonderful. They truly know what they are talking about, and they actually care about you. They really helped put my nerves at ease. Thank you so much!!!! Alex Los Angeles, CA
  • Thank you for all your help. It is nice to know that this service is here for people like myself, who need answers fast and are not sure who to consult. GP Hesperia, CA
  • I couldn't be more satisfied! This is the site I will always come to when I need a second opinion. Justin Kernersville, NC
  • Just let me say that this encounter has been entirely professional and most helpful. I liked that I could ask additional questions and get answered in a very short turn around. Esther Woodstock, NY
  • Thank you so much for taking your time and knowledge to support my concerns. Not only did you answer my questions, you even took it a step further with replying with more pertinent information I needed to know. Robin Elkton, Maryland
 
 
 

Meet The Experts:

 
 
 
  • Tim's Auto Repair

    mechanic

    Satisfied Customers:

    7641
    Have owned a repair shop for 25 yrs.
< Last | Next >
  • http://ww2.justanswer.com/uploads/TI/tim37857/2011-10-28_23053_S6301814.64x64.JPG Tim's Auto Repair's Avatar

    Tim's Auto Repair

    mechanic

    Satisfied Customers:

    7641
    Have owned a repair shop for 25 yrs.
  • http://ww2.justanswer.com/uploads/DT/dt69nova/2012-6-15_234154_pic1.64x64.jpg Dave Nova's Avatar

    Dave Nova

    Chevrolet Technician

    Satisfied Customers:

    6870
    ASE Master Certification. GM World Class Certification
  • http://ww2.justanswer.com/uploads/ggrote1/2009-06-27_031011_me.jpg Gary's Avatar

    Gary

    Chevy Technician

    Satisfied Customers:

    5404
    15 years GM master tech
  • http://ww2.justanswer.com/uploads/testedtuff/2009-09-26_170108_pictures.jpg John's Avatar

    John

    Master A.S.E Automotive technician

    Satisfied Customers:

    4071
    A.S.E MasterTechnician A1-A8 w/L1,38 years experience General Motors Master Technician
  • http://ww2.justanswer.com/uploads/RO/rodcuda/2011-7-25_224114_Donhoff1.64x64.JPG Neal's Avatar

    Neal

    Chevy Mechanic

    Satisfied Customers:

    2306
    Shop Owner and Mechanic on multiple makes.
  • http://ww2.justanswer.com/uploads/goodwrench9124/2008-11-09_220838_dscf0007.jpg goodwrench9124's Avatar

    goodwrench9124

    ASE Certified Technician

    Satisfied Customers:

    2041
    Ase Master Certified, GM Master Certified Tech. Awarded GM Top performer, Hybrid certified
  • http://ww2.justanswer.com/uploads/DR/drivefast1971/2012-1-12_172422_0009051tQKh.64x64.jpg Ron Z.'s Avatar

    Ron Z.

    - Chevy Tech -

    Satisfied Customers:

    1912
    18+yrs experience. State Inspector and Chevy Diagnostics