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Ask GM Tech (Cam) Your Own Question
GM Tech (Cam)
GM Tech (Cam), Chevy Technician
Category: Chevy
Satisfied Customers: 29396
Experience:  GM Grand Master Technician 2007. 14 years experience.
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2001 gmc: replaced my fuel tank pressure sensor..wont shift

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I have 2001 gmc sierra and i am getting dtc code of po452 fuel tank pressure,i replaced my fuel tank pressure sensor but i still get the same code,my gas Gage does not work and the the low fuel light is on as well as ses light, the truck runs fine but the transmission wont shift in to the passing gear.After trying to reset the dtc it comes right back on as well as the dtc code PO122 and PO452 p/d
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GM Tech (Cam) :

The P0122 is a throttle sensor code.


yes when i reset the dct i will be able to clear it but when i try to run diagnostics readings the code and PO452 ,and PO452 p/d as well as the PO122

GM Tech (Cam) :

OK, if the P0122 resets then you have a bad sensor, bad wiring or the the PCM. I suggest to check the wiring and the terminals in the connector. IF they are good then try a sensor.

GM Tech (Cam) :

As for the P0452, same thing, but the sensor is not the issue if you tried it. The wiring and terminals are common for failing.


do you think that any of these codes have anything to do with the transmission not shifting in passing gear?

GM Tech (Cam) :

Yes the P0122 will. The computer needs to know the throttle position to know what gear to put it in.


I have been leaning toward the ecm its self

GM Tech (Cam) :

I would not just yet. Far too many are replaced and not the cause.


ok i will check my connections once again and run my scans,The voltage is about 5 volts at the connectors right?

GM Tech (Cam) :

Yes they use a 5v reference.


i will contact you as soon as i check this out ok? thank you

GM Tech (Cam) :

You can reply at any time for follow up information regarding this issue, even after you accept my answer and I will reply.



GM Tech (Cam) and 5 other Chevy Specialists are ready to help you
Customer: replied 6 years ago.
I do not have any other codes except PO452,i see online that there is a new kit for rerouting the fuel tank pressure hose but the dtcs are different then mine,i have tested all of the connectors on ftp senser and the ecm connectors and everything test out except the the voltage refferance.Is there any known problems with my truck and any service bullitens that has anything to do with problems ?

No bulletins on this issue.

Did you do a pin drag test? We do something called a pin drag test. This is done one the female terminal with a new male terminal from the GM kit. We insert it and then see how it feels to pull it out. If there is no resistance and the terminal is loose in there, then we know the female terminal is stretched.

Customer: replied 6 years ago.
I am contacting you on the same answer session i paid for ,i need some more info,and i dont know how to continue our session without paying again.

What further info do you need?


Customer: replied 6 years ago.
Well i have to the conclusion that i have a bad ecm my code is still there PO452 and i cannot get rid of it i have tested everything to no a vale,This problem does not effect the performance only that annoying ses light,and the low fuel massage as well as the gas gage on empty.I hate to replace the ecm because of this problem,have you had this repair come up before?, and what did you do to correct if?

This sensor will not cause the low fuel message, that is a separate sensor, but is read through the PCM. It may be, but often it is wiring.

YOu did check under the fuse block? Mice love that area.

Customer: replied 6 years ago.
No i have not looked at that yet,i hade this same problem about two years ago with the low fuel and gas gage showing empty, so i took the ecm off and sprayed brake cleaner or carb cleaner on the contacts and plugs and the problem went away for a while,and when it came on again latter i replaced the fuel pump and sensor,this seemed to fix it two, but both of those times i never had a code set.

Check that first and see. LEt me know


Customer: replied 6 years ago.
Thanks Cam,but how do i get in contact with you without paying again?
Customer: replied 6 years ago.
Thanks again and god bless you to.