[Grand Joe]

Hi, all... I need some help... I bought a used 2002 Grand Cherokee.. everything was going fine untill October... Thats when i heared a high pitch sound when ever i came to a stop... Also my low coolant alert came on... I took it to the dealer on 1/13/06 because i that high pitch sound got really loud... They said it was the silanode (sorry about my spelling) and there was not coolant leak... My truck had the chime alert came on three times for coolant.. Replace the coolant and three weeks later the chime came back on... Now my check engine light came on and it gives the me codes for PO446 and PO456... Now the upseting part right now, that a new sound is coming from the engine when i stop... it sounds like a cat purring... Now i don't know if i should trade it in... ... anybody can help??

[MidniteSquirrel]

So you're getting a P0446 and a P0456?

P0446:
Evaporative Emission Control System Vent Control Circuit


P0456:
Evaporative Emission Control System Leak Detected (very small leak)

What it also says for the P0456:
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.



All informatino gathered from www.wjjeeps.com


My question is: Have you seen if any TSBs have been performed on the vehicle?