Please explain this code: P0466 Purge Flow Sensor Circuit Range/Performance

[GasSavers_StanleyD]

The followingScanguage code came up in '97 Toyota 4 Runner:

P0466 Purge Flow Sensor Circuit Range/Performance .

Anyome know what this is? Is is related to O2 sensor or Mass Air Flow sensor. I have know idea what this is and would like to know what it does and an idea of how much it costs to replace. Can I do it myself or is this shop-only job. Im a little mechanical but dont really know much. I also dont want to get railroaded by mechanic by going there without any knowledge or info.
I need to get the car inspected but the engine light came on and according to Scanguage and OBD2, its not ready because ofthis crap. Ive cleared the code, bu the Scanguage still reports that the car is not ready for emissions testing. I wil have to figure outwhat test is not complete. Im hoping that there a car-techy here that can help.

[bfg9000d]

Congrats on checking the codes on your car. You either have a vacume leak or it could be the evaporative purge flow sensor. The PFS is a three-wire thermistor, with a battery voltage feed, a ground wire, and a signal wire going to the powertrain control module (PCM). The wire going to the PCM has 5 volts on it with the sensor disconnected, which is sent out by the PCM. The sensor then varies the resistance to ground based on the amount of flow through the sensor. As the airflow increases, the resistance increases proportionally, and the voltage increases as a result. The PFS is located between the engine and the canister purge solenoid. Depending on the vehicle, there will be either ported or manifold vacuum to the system.

When the PCM decides to test the system, it energizes the canister purge solenoid, and then monitors the voltage change on the PFS. A typical system starts out with the PFS voltage being somewhere between 0.7v and 1.7v. Once the canister purge solenoid has been energized and there is good airflow through the system, voltage should increase by approximately 1.5v.

The key is to make sure the airflow is good. One way to do this is to remove the hose from the charcoal canister so that it's open to atmosphere, and then manually ground the canister purge solenoid. The hose should then have good, strong vacuum from the engine. Obviously, if it's a ported vacuum system, it will be necessary to rev up the engine to create a vacuum on the system. If airflow through the system is good, and the voltage on the purge flow sensor does not change accordingly, verify that the power and ground feeds are OK. Then make sure there is 5v on the signal wire with the sensor disconnected to verify that the wire is not shorted to ground. If everything checks out OK, but the sensor voltage does not increase properly with increasing airflow, then you have a bad purge flow sensor. If the airflow is not good, check for a bad canister purge solenoid or blocked/collapsed hose.

[GasSavers_TomO]

Check to make sure your gas cap is on tight too. It sounds like that code is related to the EVAP system for pressurizing the gas tank.

[ffvben]

Purge flow sensor is usually in the same line as the canister vent sol. the cv sol. lets the fuel vapors that have build up in the charcoal canister, run up to the engine to get re burned - the purge flow senses the fuel vapor flow and i think, lets the ecm/pcm know how much flow is detected. Most likely the purge flow sensor is shot. if it was a one time fault, after clearing the code, you may have to drive 100-200 miles to reset the complete the drive cycle.

[bfg9000d]

normally if the code came up there is a problem with the vehicle. Clearing the codes will hide the problem and the code will probably come back up. This has been my experience atleast with stuff like that.

[GasSavers_StanleyD]

Originally Posted by bfg9000d

normally if the code came up there is a problem with the vehicle. Clearing the codes will hide the problem and the code will probably come back up. This has been my experience atleast with stuff like that.

BFG, Tom and FFV, you guys are the greatest. Thanks for the info and the good advice. Naturally, I have no idea where this hose, charcoal canistor and the solenoid are, but at least I will be able to take this to the mechanic armed with some info and can 'ACT' like I know what Im talking about so there is less chance of me being 'girly ripped-off'. Im hoping that its a hose but its prob the purge sensor itself. Just hoping that its not an expensive sensor especially if its a dealer-only piece. (Pep Boys does not carry and says its dealer part)

Your explanations are better than what I was able to find out online. Much more layman. Even better, you guys provided SOLUTIONS to the problem that was not written in mechanic jargon and easy to understand. I'll try and locate the hose and inspect for any leaks, soft spots or loose connections, but I suspect that I'll be taking this to the mechanic/dealer for a purge sensor replacement. Thanks again !!!!

This site is great. I'll keep you guys posted. Luckily this is no 97 4Runner and not on 98Camry which looks appears to be giving me a 37mpg tank right now (EPA=30hwy, 28hwy old EPA)