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2007 Jeep Commander
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4 Posts
Discussion Starter · #1 ·
October 24 my check engine light went off and threw code PO456. The next day I took it to get checked out and was told it wasn’t a big deal, possible gas leak or needed a new gas cap. Last week the light went off. Yesterday my car randomly started shaking and the check engine light flashed. I got my car to the auto shop within 5 minutes of that. Today they tell me my entire engine likely needs replacing. Does that sound right? Last month they said everything looked fine. Unfortunately that’s not documented.
 

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2006 4.7L Sport, QT-II 4WD
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182 Posts
If my memory serves me right, the P0456 code is a "Small Emissions Leak". A lot of times, it is as simple as a bad gas cap. I've currently got that code for my check engine light, been chasing it down for years. I pretty much just put up w. it now.

I'd say you're dealing with two separate issues.
 

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Super Moderator
2006 Commander Limited, 5.7 Hemi QD2
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@debord2009
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Registered
2007 Jeep Commander
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4 Posts
Discussion Starter · #4 ·
If my memory serves me right, the P0456 code is a "Small Emissions Leak". A lot of times, it is as simple as a bad gas cap. I've currently got that code for my check engine light, been chasing it down for years. I pretty much just put up w. it now.

I'd say you're dealing with two separate issues.
What do you think the second issue could be? I’m reading spark plugs or something with fuel lines but they are trying to tell me the entire engine is bad. I was driving my car just fine and all of the sudden without warning my car’s engine is bad?
 

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Super Moderator
2006 Commander Limited, 5.7 Hemi QD2
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1,291 Posts
It helps us a lot if we knew what engine you have. There are 4 different engines in Commanders. Also see my post above and make a signature wit your commander details.
 

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Alright I think I added it correctly. It’s a 2007 with Hemi
@debord2009 ;

We need to know 2WD or 4WD

If it's 4WD, which 4WD system - QT-I, QT-II or QD-II?

Which trim package do you have - Sport, Limited or Overland?

How many miles are on it?

New members are responsible to read ALL of the new member requirements & guidance before you post anything.

Important New Member information, Forum requirements & Forum rules. | Jeep Commander Forum

If you need help with any of this - ask.
 

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2007 Jeep Commander
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4 Posts
Discussion Starter · #8 ·
Oh okay, I can add more information when my husband is home. I know it is Limited. I think 2WD but I’ll have to verify that. It has 126k miles on it.

Mechanic called and said it’s too dangerous to restart. The messed with coils and still throwing up 1,2,3, and 8 misfire.
 

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Oh okay, I can add more information when my husband is home. I know it is Limited. I think 2WD but I’ll have to verify that. It has 126k miles on it.

Mechanic called and said it’s too dangerous to restart. The messed with coils and still throwing up 1,2,3, and 8 misfire.
I will add the information you gave me so far, to your signature, thank you.
 

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October 24 my check engine light went off and threw code PO456. The next day I took it to get checked out and was told it wasn’t a big deal, possible gas leak or needed a new gas cap. Last week the light went off. Yesterday my car randomly started shaking and the check engine light flashed. I got my car to the auto shop within 5 minutes of that. Today they tell me my entire engine likely needs replacing. Does that sound right? Last month they said everything looked fine. Unfortunately that’s not documented.
Jeep WJ Grand Cherokee Diagnostic Trouble Codes | JeepSpecs.com

P0455 (M)Evaporative Emission Control System Leak Detected (large leak)A large leak has been detected in the evaporative system. See TSB 25-001-02. Also, possible faulty or loose gas cap. Note: The respective Powertrain Diagnostic Procedures Manual will direct the technician to determine if the vehicle evaporative system has an external system leak. Examples of some external system leaks are: a loose gas cap, a disconnected evaporative system hose, or a loose hose connection. Remember that the evaporative system may also have an internal system leak. This internal leak may be caused by an intermittent or permanently stuck open Duty Cycle Purge (DCP) valve. This leak source is considered to be internal because any escaping emissions enter into the engine system and not directly into the atmosphere, unlike an external leak. An internal leak may cause one of the above DTC?s. Possible causes of a stuck open (intermittent or permanent) DCP valve are: 1. Corrosion due to system moisture or possible water intrusion into the system.


P0456 (M)Evaporative Emission Control System Leak Detected (very small leak)A 0.020 leak has been detected in the evaporative system. See TSB’s 25-001-02A, 18-002-03 and 25-004-01. Also, possible faulty or loose gas cap.

(Also see Notes in P0455 above). Does customer regularly commute on a steep grade (down hill grades in excess of 10%? Has the Leak Detection Pump Operation and Diagnosis booklet (Publication No. 81-170-000606) been used to assist in the diagnosis?
Review and if necessary, perform TSB 18-010-02. Be sure to completely read the TSB. The fix for the condition is a PCM replacement, not a reprogramming of the controller. Be sure that there is not any leaks in the system. This TSB applies in a very limited number of cases and usually in mountainous regions. TSB 18-010-02 Is a PCM replacement correct an erroneous MIL illumination for SAE P0456 that sets when driven on steep grades.
 
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