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Can anyone help me with 2010 Hyundai Veracruz drive cycle steps/procedures to clear a stubborn "Permanent P0456 EVAP very small leak" code? I have replaced the gas cap with genuine hyundai cap and replaced the purge valve solenoid.I have tried different generic drive cycles but I return to the parts store for scan and get "P0456 Pending" and "P0456 Permanent". they clear the pending and I've tried several times to do generic drive cycles (idle 1 minute, drive 20mins highway speeds, 20 minutes in town, stop, idle 1min, turn key off).

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I found this PDF with Drive Cycles for Hyundai's, which should include your Veracruz. Here are the relevant parts of the Drive Cycle to include the graphic from the PDF:

General Instructions:

enter image description here

Drive Schedule Notes:

  1. Coolant needs to be within 0 to 40C (0 to 104F) at start
  2. Fuel level must be above 15%

(Pᴀᴜʟsᴛᴇʀ2 Note: I've seen a lot of drive cycles which require you to be between 1/4 and 3/4 full. Do this.)

  1. When decelerating from 50-55 mph, there needs to be at least 5 sec of fuel cut-off; it's best to close throttle as soon as possible for 5 secs to assure decel fuel cutoff occurs.
  2. Try to maintain consistent throttle as much as possible during the steady state speed portions of the drive cycle.

Cautions:

  1. This schedule is best driven on a dyno if available, otherwise find the best road with least traffic.
  2. Obey speed limits and drive safely.
  3. If you lose the schedule due to traffic, attempt to get back to it when conditions are safe to do so.
  4. Keep your eye on the road and avoid looking at the schedule constantly; its best to have a passenger describe the schedule to you while driving.

If the codes do not clear right away, do not use the scanner to clear them. This resets ALL eight of the readiness codes and you'll be restarting the Drive Cycle from scratch.

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Although this does not answer your specific question, I strongly suspect that you have not fixed the problem.

If your auto parts store is clearing all codes and it is returning, you probably have a small leak in a rubber hose or rusted hard line. Gas cap and purge/vent valves would more likely result in a code for a gross leak.

I don't know the Veracruz, but I have struggled with several Elantras. The valves are next to the gas tank, under a plastic cover which is virtually exposed to the elements and accumulates all manner of rusty salty crud. The components are connected with molded rubber hoses which rot, and are "sealed" with cheap wire clamps which rust away. In addition, the lines from the evap canister/valve area to the engine run along the driver-side frame rail and are also subject to rot and rust. (Insert Hyundai pejorative here...)

You may need a so-called "smoke test" in which the entire evap system is filled with slightly pressurized mineral oil smoke from a special device while the evap valves are electronically exercised with a scan tool. If you "let the smoke out" it will be obvious where it comes from.

If I were a betting man this will be somewhere around the evap canister/valves or somewhere along the lines that run back up to the intake.

Also, pay particular attention to the prerequisites for the drive cycle. Most evap monitor tests will not even execute unless a set of conditions are met, including fuel level (Paulster's find says above 15%, but many will not execute above 75% fuel level as well.) However, that point is completely moot if the codes are returning.

An incomplete drive cycle does not set a code!

ON EDIT:

Please don't obsess over the word "permanent". There is really no such thing in the context you describe. I suspect the proper clearing sequence is not being executed. You should be able to clear the code with Key On Engine OFF, and then immediately scan for codes. If the code is still there (without starting the engine) the code was not cleared properly, or there is something else quite obscure wrong (bad ECM). Of this I doubt.

PENDING refers to a code that has been set, but has not repeated itself enough times to verify the fault exists over possibly several drive cycles. Note that Pending does not set a CEL, but certainly can be seen with a scan tool.

"PERMANENT" refers to a fault that has been detected two or more times (or is a continuous problem, e.g. broken wire to O2 sensor heater) and THEN (timing and iteration thresholds depend on the vehicle, software, and the specific test) is promoted from Pending to Permanent. "Permanent" is also just a name for an actual CEL that sets that code and illuminates the CEL.

If the problem is repaired, it may allow a permanent code to be cleared after some number of successful drive cycles. This can be so many it almost always makes sense to clear with a scanner to verify the fix.

Keep in mind that Evap tests are monitor tests and have complex pre-requisites to run. There is no "instant" P0456 test that I'm aware of. More likely the code has not been successfully cleared before you attempt a drive cycle. And, if at any time, the system still senses the problem, the code will be re-established before the drive cycle is complete.

You need a clean "no-codes" found state before you even attempt a drive cycle. If you cannot clear the code before you start the engine, it will be a long fight to try and clear it with drive cycles.

I'm not certain on a Hyundai, but Subaru, for instance, needs to have the codes cleared, the key turned off, and then the key turned back on (but not started). The CEL should extinguish a few seconds after the CEL lamp test. And the scanner should show no codes of any kind. If you can't accomplish this, something else is wrong.

It is specifically the evap test that checks the system integrity (likely with a sensor) that ascertains whether there is a leak. That leak is a "vacuum" leak of sorts, and is only able to execute with the engine running (to provide a source of vacuum). As far as I know, no Evap test can legitimately run (and set any type of code) with the engine off.

Prove to yourself first that the code is cleared. If you can't clear it, the scan tool may not be sophisticated enough, or the proper procedure is not being followed. What you can do is disconnect the battery negative for 15 minutes, reconnect, and immediately check for codes without starting the engine. (Do this easily without a scan tool by simply observing if the CEL goes out after a short pause.) If there are no codes, the internet claims a Hyundai needs TWO completed drive cycles without fault to enable the EVAP readiness monitor. If the code comes back before the drive cycle(s) are complete, in all likelihood there is still a leak somewhere.

  • thank you. The code is not returning. the code is "Permanent" P0456. it does not go away after the scanner resets the engine light. it. That is why i'm hoping that a correct drive cycle for that 2010 veracruz will let the computer accept the readings and clear the "Permanent" status of the code. if it came back after that I could see that the issue is still needing to be fixed. – d. michels Jan 9 '18 at 4:06

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