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Engine Code P259E: Turbo "A" Boost Control Position at Low Limit

5980 Views 7 Replies 3 Participants Last post by  MyBlueJeanTruck
I have been traveling; 8000 miles since June 1. I was towing ~7000lbs at 10,000 altitude when a check engine light came on and power was reduced. I was amazed I coild still tow at 65mph with reduced power, but I was barely able to gho 65.

Anyhow, one local "expert" said this happens with newer trucks when they are normally driven at lower altitudes and then taken to high altitudes. I live atr sea level.

So, the code is reset and the truck is "normal again".
Time to wait and see.
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An east fix? So a customer with an OBDII scanner can just push reset and return to full power? I wasn't aware it was possible, but that sounds promising.
I was wrong about back to full power. But the check engine is cleared. I drove 80 mountain miles yesterday and the turbo won't go above ~50% of max boost PSI. I forgot to mention that I have had the service for the EGR screws getting into the engine; mine are replace with spot welded screws. So, I am not super worried that this code will lead to engine failure for me. Only a little worried.
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@MyBlueJeanTruck - slightly confused here.... Did you reset the code via FORScan or did your dealer clear the code? If the latter, then why is turbo not going above 50% of max boost PSI?
I got a message about reduced power and P259E.
I borrowed a scannaer at NAPA to read the code, then deleted it.
Then, because i was suspicous about the code being cleared not being cleared all the way, I disconnected the battery negative terminal for 30 minutes.
Then I went to Phil Long Ford in Denver. They tested everything and said the engine was delivering full power. I was out of towner and they took me in right away. A good dealership.

So, a couple things happened:
1) I got an engine code at 10,000ft pulling a 7000lbs trailer.
2) I cleared the code and the engine returned to "full power at 10,000" where I was", but I didn't realize it was back to normal. When I unhooked the trailer, the boost psi was goiing as high as I was used to seeing. My perception of full power comes from sea level.

The guys at Phil Long performed all tests that can give the code and none of them failed.

So, altitude did it.
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@MyBlueJeanTruck - thanks for the clarification, as I learned that altitude impacts turbo boost and performance, and your return to full power was verified by a Ford dealer who took care of you as a Ford customer.
They did some tests at the dealership to try and find a fault, but they were not successful. I think the the real issue is that the truck towing specification for altitude is forgotten?
Don't give them too much credit at the Ford dealer. I spent $60k on the truck and its under warranty. They did get me in and out quickly, but with no diagnosis. They said: nothing wrong.
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