Can permanent engine codes be cleared without taking my vehicle to the dealership

Tiny
TRUSSELL1180
  • MEMBER
  • 2011 JEEP GRAND CHEROKEE
  • 3.6L
  • 6 CYL
  • AWD
  • AUTOMATIC
  • 92,000 MILES
Had P306 and 305 codes. Changed plugs and coils. Cleared codes with an Actron code reader. Was off but came back on. Shows permanent codes stored. Was wondering if I have to go back to the dealer to get these cleared?
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Saturday, April 1st, 2017 AT 8:06 PM

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Tiny
CARADIODOC
  • EXPERT
What came back on, the codes or the Check Engine light? When you can feel a misfire, it is because you are feeling the rotational speed of the crankshaft slowing down momentarily when that misfire occurs. The Engine Computer detects misfires the same way, but it can also see misfires that are too subtle for the driver to feel. Are you sure the problem is solved? Chrysler has extremely little trouble with their injectors, but you might consider switching some between cylinders to see if the misfires move to a different cylinder.

Once you restart the engine after the repairs have been performed, the Check Engine light should be off until and if the problem occurs again. The fault codes should erase automatically after fifty starts if the problem does not occur again, at least that is what would happen on older models. Codes in most computers can also be erased by disconnecting the battery for a few seconds, but I do not like to recommend that any more. Some manufacturers have purposely designed in tricks to force you to have the vehicle towed to the dealership to have multiple computers unlocked after simply replacing the battery. Chrysler has always been the leader, going way back to the fifties, in developing innovations that directly benefited their customers. Some other manufacturers are the leaders at coming up with innovations that benefit them, at the expense of their customers. Unfortunately the entire industry is full of copycats, and any innovations, good and bad, are soon adopted by all the manufacturers. I have a 2014 Ram truck that I know I can disconnect the battery without consequence, but for people researching this topic, I want them to understand disconnecting the battery today should be avoided whenever possible.

If you use a regular scanner, not a code reader, you have the option of seeing how many engine starts have taken place since each fault code set. If you see "1", the problem is still occurring. If you see a higher number, the problem did not occur on the last drive cycle.

Now I am going to tell you more than I know. I have heard there are times when a fault code can set in one computer, then that one transmits that data to the other computers. While you are erasing the code in the Engine Computer, it may immediately relearn that code from a different computer. Code readers can only erase codes in Engine Computers, not the many other computers. Where this would be an issue is when another computer cannot perform some functions properly when there is a potential misfire. Specifically, I am thinking of anti-skid and stability control systems. I do know those work in conjunction with a properly-working anti-lock brake system, and some of that data is shared with the Transmission Computer. While you may not be able to erase all the fault codes with a code reader, any independent repair shop will have an aftermarket scanner that can read and erase codes in all the computers. I just used my friend's Snapon Solus Edge tonight. That can read and display all the fault codes in every computer, all at once. No need to search every computer or wonder if you missed anything. I would approach a shop owner during his lunch hour and ask if a five or ten-dollar tip would get the codes erased without writing up a repair order. If the codes set again after that, you will know the problem has not been solved yet.
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Saturday, April 1st, 2017 AT 9:49 PM

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