Help with engine codes

Plumber1

Tito's, Tacos and Trails
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San Ramon, CA
So my check engine light came on, so I borrowed a scanner and got the P0456 code. Looks as this in something to do with the Evap system. Also not sure what this other screen is telling me ? HRT, DTC, Pd DTC. I am no mechanic so any help would be appreciated

Thanks

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dtc means diagnostic troublecode , pdc means means pending code, it is about to throw another -that scanner may show it too - hrt is heater readiness test - this means the pcm is not firing up an o2 sensor to preheat it - the hrt may be pending

the post above is correct, and make sure it wasn’t fueled up running by someone-

Yours is low mileage so I doubt it is serious - I’m tagging @Wranglerfix because he will know if these are indicative of pcm failure - it was on mine - the pcm was not telling the sensor to test . A scanner will really educate you - worth the investment. I may get a Bosch eventually, or just not get 04-06 models😩😂

The highest priced Zurich scanner at harbor freight can read live data and may be able to trigger the evap system , and it is only 159.00 I think - I just got one - handy with an 04-06 . Mine was throwing out more codes than a hungover building inspector with a bad attitude. The evap system is plumbing , no joke- and can be the pump, the purge valve or a hose- or the pcm is behind both possibly , but I may be wrong on the possibility of that.


Good luck, please keep us posted so we learn too.
 
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There is a TSB that California acknowledges on certain late model TJs- the 02 sensors are governed by the ASD Relay - automatic shutdown - if the key is turned in but it isn’t cranked in a certain time frame the asd kicks in , it is a security feature-this kills the o2 sensors as they preheat , and triggers a code - the TSB shows how to bypass it -
 
The I/M readiness tests get restarted every time codes are cleared. The green check marks mean the test is complete and satisfactory. The red Xs mean it’s either incomplete, or it was completed, with a code present. The grey crossed-circles mean that the test is not applicable to your PCM.

You are correct - your EVAP system has a leak. If the gas cap doesn’t solve it, a smoke test will reveal the source.

Regarding the incomplete HRT, there’s a TSB for that - it’s a wiring defect. (Edited to add - AndyG beat me to it)
 
The I/M readiness tests get restarted every time codes are cleared. The green check marks mean the test is complete and satisfactory. The red Xs mean it’s either incomplete, or it was completed, with a code present. The grey crossed-circles mean that the test is not applicable to your PCM.

You are correct - your EVAP system has a leak. If the gas cap doesn’t solve it, a smoke test will reveal the source.

Regarding the incomplete HRT, there’s a TSB for that - it’s a wiring defect. (Edited to add - AndyG beat me to it)

Good post , I want to add that people with pear shaped bodies should not wear fruit colored clothes.
 
Aren’t fruit-colored clothes pretty much ubiquitous? If you rule out the colors that fruits display, what’s left?
 
I recently got the code from filling up and not properly tightening my gas cap. The smallest leak can cause the code and can be as simple as a gas cap replacement to dropping the tank. Go forward with an ounce of optimism and a gas cap!

  • Evap System Hose– The hose that carries the fuel vapor from the fuel tank to the intake manifold can begin to leak. This will cause the P0456 code. Look for either a tear or hole in it. This is one of the most common issues that causes the code.
  • Vapor Canister Purge Valve– One of the most common causes of the P0456 code is the vapor canister purge valve. It’s really easy to replace. There are a few clips that you need to find and remove.
  • Fuel Tank Sending Unit– It is possible for the gasket that attaches the fuel sending unit to the gas tank to go bad. This can reduce tank pressure and throw the code.
  • Fuel Cap– A bad fuel cap can cause the code to be thrown for sure. Often, you’ll get a message informing you that the fuel cap is off even when it is on. If you are getting that message, plus a P0456, it may save you a ton of time and money to replace the fuel cap and see if it goes away.
  • Fuel Filler Neck– There is often a gasket where the fuel filler neck connects with the gas tank. This gasket can dry out, especially with vehicles that spend their time in dry climates. When it dries out, the fuel tank can’t hold pressure anymore.
P.S.

You can rule out the pcm and let us know what you find out!
 
The I/M readiness tests get restarted every time codes are cleared. The green check marks mean the test is complete and satisfactory. The red Xs mean it’s either incomplete, or it was completed, with a code present. The grey crossed-circles mean that the test is not applicable to your PCM.

You are correct - your EVAP system has a leak. If the gas cap doesn’t solve it, a smoke test will reveal the source.

Regarding the incomplete HRT, there’s a TSB for that - it’s a wiring defect. (Edited to add - AndyG beat me to it)

How do you do a smoke test ?
 
I've had Evap system leaks on every car I've owned in the last 20 years (I keep cars forever), so I made a smoke tester out of a clean paint can and a propane regulator years ago. Recently I bought a better (more durable, and with an electric oil burner) system from these folks, based on a recommendation on this forum, I think:

https://www.autolinepro.com/collections/automotive-smoke-machines
Their economy version is similar to what I built years ago, but I bought the shop version from them. The economy version would work just fine. What you do is attach the inlet hose on the machine to an air compressor and the outlet to your Evap system (I haven't had to use it on my LJ, yet, so I don't know if there is a test port on it). You then pump smoke into the system and look for leaks.