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Junior Member
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17 Posts
Discussion Starter #1
I had my truck (2002 chevy 1 ton, duramax, w/ Allison trans) put on a computer and received the following readings:

1.) PO843 - Voltage signal from transmission fluid pressure sensor/switch 'A' too high for current operating conditions.

2.) PO540 - Malfunction exists in electrical curcuit for intake air heater.

Can you guys tell me what these readings mean, and what i need to do to fix 'em.

Thanks,
Shad
 

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Registered
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3 Posts
Hey Guys! New here, Got the same problem with the PO540 code showing on my 03 Duramax, I have an OBDII and it reads intake air heater malfunction. I am assuming this relates to the Glow Plugs ( I could be wrong ) , I traced out all the wires and everything looks fine,tested the glow plugs-fine, trucks starts really well in -20 celcius Newfoundland Winters without the block heater so I think the glow plugs are working properly. When I erase the code with my handheld the engine light stays off for 3 or 4 days then it will come back on a cold start-up! I read somewhere about a heater being combined in the mass air flow sensor, could this be the problem?? Other than that the truck is great! An help would be greatly appreciated!!!
 

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Afrye
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18 Posts
I just had the same problems on my cc dually, we are putting a new relay in today to see if that helps my intake heater code, tested the heater and works fine, so i hope its just a relay, I dont know if my trans code was the same though, i cant remember what it said but we changed the nsbu box on the side of trans and havent seen the tranny code since, but check the to plugs that going into the box for corrosion. Ill let you know later if the relay fixesw my problem.
 
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