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6th Gen ('00-'05): P0440, 2002 mc ss

Old 03-28-2019, 06:39 AM
Thread Starter
Join Date: Oct 2018
Posts: 3
Default P0440, 2002 mc ss

popping a code P0440. was popping that code earlier, plus a P0172. Fixed the P0172 with EGR and ports cleaning, efi cleaners, new upstream O2 sensor, MAF sensor needed replaced too, throttle body cleaning, checked the pressure regulator, changed plugs, new pcv, new air filter, new gas cap and new fuel filter. I relieved pressure off fuel system prior to doing all these. I have reset the codes twice since doing all these repairs. 0440 still coming back.

So I have done a number of maintenance issues to the car. 93k on it. this dang P0440 is driving me crazy. any ideas? and anyway of checking said ideas?

One thing of note, I have found when replacing the plugs 9(did it 40K and now again), what a job on the back ones, I was sitting on top of engine, lol, and I could smell gas. Which seems like it is coming in at the top/back rail fuel line. I can push down on the connector and gas will come out. normal? I tired on the front rail/fuel line, this did not respond with gas coming out. So I am assuming, the o ring is bad or connector? Could this be popping the 0440 code?


Last edited by Apachie; 03-28-2019 at 06:45 AM.
Old 03-28-2019, 07:40 AM
Join Date: Nov 2017
Location: Isanti, MN
Posts: 825

This indicates that a part of the EVAP control system is no longer fuctioning correctly. The EVAP system consists of many parts, including (but not limited to) the gas cap, fuel lines, carbon canister, purge valve, and other hoses

The (EVAP) emission control system prevents the escape of fuel vapors from a vehicle's fuel system. Fuel vapors are routed by hoses to a charcoal canister for storage. Later, when the engine is running a purge control valve opens allowing intake vacuum to siphon the fuel vapors into the engine.


You likely won't notice any drivability problems.


A code P0440 could mean one or more of the following has happened:
  • The gas cap is not installed or working properly
  • The purge solenoid has failed
  • The canister is plugged and not working properly

Possible Solutions

With a P0440 OBD-II trouble code, diagnosis can be tricky at times. Here are some things to try:
  • Remove and reinstall the gas cap, clear the code, and drive for a day and see if the codes come back.
  • Inspect the EVAP system for cuts/holes in tubes/hoses
  • Inspect for damaged or disconnected hoses around the Evap purge solenoid
  • Check and/or replace the sensor
  • Check and/or replace the purge valve
  • Have a professional use a smoke machine to detect leaks
I also would be pulling that injector rail and fixing that fuel avoid a fire. Don't forget to check the purge solenoid by located in the rear quarter by the gas cap. Good luck

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