Q: was getting PO440 CODE.

asked by on February 15, 2017

getting po440 code on 2001 s10 4cyl.changed vacum lines ,took off and checked vent and purge valves ,they operated as they should off vehicle ,but when put back on would not work. Had 11 volts at plug in to valves. What could be cause of valves not functioning.

My car has 99000 miles.
My car has a manual transmission.

These valves are controlled by the PCM so the circuit will not be closed until commanded by the PCM and that closure can be through the ground side. If the circuit is competed through the ground side, you will always be able to detect battery voltage if you measure the solenoid plug hot side to body ground, but if you check continuity on the plug side ground to vehicle ground you will find the circuit open simply because the solenoid is not supposed to be commanded on at the time you are checking for operation. The bottom line is if the solenoids test OK off the vehicle, re-install them and look elsewhere for the problem. You might want to check the wiring though because 11 volts is a little low, unless the battery is also low. You should see close to battery voltage at the solenoids. If not, there is too much resistance in the circuit.



Often code P0440 will set because the gas cap is not sealed or working properly, the purge solenoid has failed or the canister is faulty (plugged, etc.). Check the cap (ideally use a new OEM cap, not aftermarket) and erase the code and see what happens. If the code comes back, you may have to use a smoke machine to check for EVAP system leaks. If you want these steps performed by a certified Mechanic, dispatched by YourMechanic right to your location, please request an EVAP system/canister diagnostic and the responding certified mechanic will get this resolved for you. If you have further questions or concerns, do not hesitate to re-contact YourMechanic as we are always here to help you.

The statements expressed above are only for informational purposes and should be independently verified. Please see our terms of service for more details

Get an instant quote for your car

Our certified mechanics come to you ・Backed by 12-month, 12,000-mile guarantee・Fair and transparent pricing

What others are asking

Truck won't crank

From your description, it sounds as though your ignition switch is faulty. If there is power on the wire when trying to crank, it could be a faulty starter. You could ask for help from a certified mechanic at YourMechanic...

Safe to drive with hole in muffler

Hi there. A hole in the muffler is typically not a really serious issue. It should be safe to drive the vehicle. My biggest concern though is the exhaust itself. If the hole is allowing exhaust to enter the cab...

Transmission makes high pitched whistle intermediatly

Hi there. The whistling noise from the transmission could be either a thrust bearing failing or a clutch pack is slipping under certain conditions. First check the fluid to the transmission and make sure that its full and red in...

Looking for info about most common OBD2 Codes

There are two (at least) quite distinct issues in regard to your general request: The first is, once a check engine light illuminates, what are the most "frequent" codes that are stored and thence downloaded, that is what does THAT...

1999 VW Jetta Poor acceleration

The check engine light tells you that the Engine Controller (ECU) has detected a fault and stored a trouble code. So the best place to begin is to have the codes read and interpreted bu a technician. It's possible you...

I was in a car accident with my 2014 Chevy cruze and I was hit on the rear driver side. My drivers rear tire's rim has a small dent.

Hi there. The light came on for the wheel is spinning on a different path than the reluctor ring can pick up on the wheel speed sensor. The wheel could be bent and causing the wheel hub to be bent...

Front engine seal is leaking

Hello, if the front crankshaft seal is leaking, the only way to stop the leak is to replace the seal. The harmonic damper needs to removed for access to the seal. Other parts may have to be removed like the...

Gurgling noise and transmission fluid leak 2009 Chevrolet Malibu

Hello - the gurgling noise is most likely a cooling system issue - perhaps overheating that has not yet caused a failure. Check coolant level (engine cold), and the transmission fluid level as well. Look for clear, pinkish (not dark)...

Car was barely turning over and would not enough to start. Kept trying and eventually everything was dead. New battery still dead

The first thing to check is to make sure the battery has proper voltage of at least 12.5 volts. Then make sure the battery cable ends are clean and tight. Make sure any corrosion is cleaned off them to give...

Related articles

P0490 OBD-II Trouble Code: Exhaust Gas Recirculation "A" Control Circuit High
P0490 means the PCM has detected an abnormally high voltage within the exhaust gas recirculation system, often due to clogging.
P0374 OBD-II Trouble Code: Timing Reference High Resolution Signal A No Pulses
What What the P0374 code means The Powertrain Control Module (PCM) has discovered a problem in the high-resolution timing reference signal. What causes the P0374 code? There may be one or more causes for the P0374 code: A...
2012 Chevrolet Traverse vs. 2012 Toyota Highlander: Which One Should I Buy?
Large SUVs are a huge and broad market, with a range of different offerings from economy to luxurious. The majority of the SUVs and crossover SUVs offer decent gas mileage, plenty of room for friends and family to ride along...