Failed E test and Pending 420/430 codes

[Angstrom]

Yesterday I failed the Etest. After recently installing the new DT headers, I now get 420 and 430 codes until the truck warms up a little. With the cracked OEM manifolds I only used to get 430. So I let the truck warm up, cleared the codes and took it in for test. Except the test can tell that the codes were deleted as there was data missing. Several of the items said "Not Ready".

I had previously ordered the URD O2 simulator, but it won't be available until the new year. Meanwhile my plates expire in a week. I tried doing the $5 O2 mod but could not find a 1 uF Capacitor anywhere so I used a 2.2uF instead. It stopped the O2 codes, but produced two others. So I removed the mod.

The shop says it takes time for the ECU to stabilize after clearing codes so they can do the test. So today, I have driven for about 2 hours and then checked the scanner. Even though the dash has not shown Check Engine light after clearing this morning, there are two codes read by the scanner that say 420P and 430P pending.

Does anyone know if this is normal or what this means to an etest?

 

[SSt4r]

I don't know what pending codes will mean to the test but I screwed up my cats a year ago and continuously got the same codes. Tries replacing an O2 sensor on one side then the air flow sensor on the other side then put both new sensors on the same side (I was hoping I'd just screwed up the sensors but apparently not) with no change. I then did the cheat of adding the spark plug antifoulers on the O2 sensors (use the purpose designed Blox Racing BXFL-00108 instead of modifying actual antifoulers) and haven't had the codes return.
I'm in the shop now having m DT headers installed so we'll see what happens when I get it back. How do you like them? I can't wait to get rid of the tick tick tick....

 

[BlackWorksInc]

I don't know what pending codes will mean to the test but I screwed up my cats a year ago and continuously got the same codes...

A "Pending" DTC is a single trip DTC in a two trip system set by the vehicle when it detects a self-test has failed once. OBDII dictates the use of "Two Trip Logic" which means that a test run by the vehicle must fail twice (doesn't have to be consecutive, just second failure after a Pending DTC is active) before the MIL is turned on. Basically it looks like this:

~Vehicle runs Catalyst Efficiency Test on Bank 1
~Test returns "Failed" status, Pending DTC P0420 is stored in ECM
~Vehicle run Catalyst Efficiency Test on Bank 1, test returns "Pass", Pending DTC still stored in ECM memory
~Vehicle runs Catalyst Efficiency Test on Bank 1 a third time, test returns "Failed" status
~Pending DTC P0420 is matured to a "Current" DTC P0420 and the MIL is turned on

[MENTION=7415]Angstrom[/MENTION]
What you're talking about is Readiness Monitors, when a DTC is cleared from the vehicle's memory it also erases stored data such as fuel trims and testing results for various monitors. Of these monitors there's 7 that are used for emissions checks. To pass an emissions check the monitors need to have run and returned a "Pass" result (some US states allow up to 1~2 monitors to not pass out of 7 without automatically failing your emissions test, I don't know how Canada deals with emissions).

The Readiness Monitors require specific requirements before the vehicle will even run the test (i.e. coolant temp must be a certain temperature, O2 Sensors are a certain temperature, vehicle is in closed loop, vehicle is at specific speed, no DTCs set, ect.), then it will run the test that meets those requirements. There is a "Drive Cycle" for essentially manually forcing the DTCs to set, but it's not usually something that can realistically be done on the open road or in a shop. Toyotas tend to be pretty forgiving though and a good 20~40 mile non-stop (i.e. do not turn the ignition off) will set almost all the monitors. The EVAP monitor is trickier to set as it usually requires you to meet a drive cycle requirement and then it can need the vehicle to sit for up to 8hrs undisturbed before it even tries to run the EVAP test. That's why it's not uncommon to have the EVAP test not run for almost a week depending on customer's habits.

Most aftermarket scantools should have a "Readiness Monitor" option where you can see the monitors and their results, usually it will be one of three statuses: "Not Ready/Not Run" "Ready/Pass" "Failed". If it shows failed, you'll see either a Pending or Current DTC stored in the ECM that requires repair and clearing before you can run the tests again.

I would recommend you read both of these threads for better understanding of the DTCs and how to go about diagnosing/repairing them:

http://www.toyota-4runner.org/4th-gen-t4rs/151487-check-engine-trac-vsc-read-me.html
http://www.toyota-4runner.org/4th-gen-t4rs/132953-toolbox-how-use.html

 

[Angstrom]

Thanks for this info. I ended up buying the URD part to fix the problem.