Any one how there have the dignostic procedure for P0443 code? I have a 1999 Cherokee Classic with a 4.0L engine.I have a CEL on with no code showing but I found this code was stored in the Data Freeze section of my scan tool.Scan tool says MIL light but scan tool reads no codes.I can click on clear codes and CEL will go out and stay out until I shut engine off and restart.Scan tool will read the same with CEL on. No codes MIL light on.I was blowing the fuel pump fuse there for a while and put a 10amp fuse in to test. Did not blow. Not siure which way to proceed.Any replies would be appreciated.

 

P0443 is an evaporative emissions code. Here is more.
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http://www.obd-codes.com/p0443

 

Does the Evap canister purge valve make a "clicking" sound while the engine is running, it's located on the driver side under the hood toward the front. I have run into a few of these that shortout internally and set what is called a "hard" code, That is a fault that is present on every key cycle. It could be that the scanner you are using just isn't picking this up too quickly. Try unplugging the purge valve and then clear the CEL codes and restart the engine, if the light stays off you need a new purge valve.

 

Took to a friends shop who comfirmed that P0443 is active.Would not show up on my scan tool. Did all testing and based on steps taken the PCM has failed.I have a friend who has a 1999 Cherokee exactly like mine. Would it hurt his PCM if I tested it on my vehicle? Where is a good place to purchase a PCM.I know they require the VIN # to program.

 

THe replacement PCM has repaired the problem.