OT - OBD2 Trouble Codes

My kid is driving a Toyota Tacoma, and the Check Engine light came on the
other day. I recorded the codes and erased them. Then I set about looking
them up. Here is a listing of all OBD II Trouble Codes. Feel free to store
it in your favorites for future reference.

http://www.wattora.com/Mods/OBDII/




My daughter's truck came back with 4 codes, P0440, P0441 (twice) and P0446.
All codes in the P04 Series are Evaporative Emissions Control System codes.
I assume this to mean they all deal with issues that can result in fuel
evaporating into the atmosphere instead of being captured and sent back to
the fuel tank. A quick glance at the list says the codes from P0440 to P0455
have to do with fuel management of fuel that was not actually used, and that
is meant to be routed back to the fuel tank to be used later.

P0440 simply says, "Malfunction".

P0441 says Incorrect Purge Flow. There are specific codes for high flow, and
open and shorted circuits. I got this code twice.

P0446 says there is a Vent Control Circuit Malfunction. I assume this to be
the code that results from not having the gas cap on right, or fully. As
with the Purge Valve codes, the Vent Control codes also break out open and
shorted circuits. In the case of 46, the code only says malfunction, it does
not say which way the malfunction goes.


Of the codes on my Toyota, the only one that leads me to replacing any
hardware is P0441, and this directs me to a Purge Control Valve. I have to
admit, I am clueless as to what or where the Purge Control Valve lives. My
strategy is to clear the codes, then watch for the Check light to come on
again, and see what is stored. My assumption is that the Emmission Control
System simply got a wild hair in its butt and set the light off. Would
anybody else make such an assumption, or would you break out the wrenches
and the checkbook, and throw a box of parts at this problem?

In message >, "Jeff Strickland" wrote:

>Of the codes on my Toyota, the only one that leads me to replacing any
>hardware is P0441, and this directs me to a Purge Control Valve. I have to
>admit, I am clueless as to what or where the Purge Control Valve lives. My
>strategy is to clear the codes, then watch for the Check light to come on
>again, and see what is stored. My assumption is that the Emmission Control
>System simply got a wild hair in its butt and set the light off. Would
>anybody else make such an assumption, or would you break out the wrenches
>and the checkbook, and throw a box of parts at this problem?

I wouldn't go throwing parts at it right away. Most likely one failure is
causing multiple codes. Of the codes you have there, I'd suspect P0446, since
it says the computer has detected a malfunction in the electrical circuit that
controls the evap system vent.

I have no clue how Toyota monitors their evap/purge system, but being able to
control the vent is a must, no matter how they do it. To leak test, the vent
must be closed to seal the system. To purge properly, the vent must be open.

I think 'wait and see' is the way to go for now.