P0121 fault code - Jeep Wrangler Forum
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Old 05-20-2013, 04:37 PM   #1
Join Date: May 2013
Location: Jacksonville Beach, FL
Posts: 3
P0121 fault code

Replaced the TPS on 4.0 inline 6 cylinder. Disconnected the battery while swapping it out. Drove the Jeep 20 miles, all speeds. When I gave it the gas to get up to 65 mph, it started bucking and wouldn't upshift (automatic). Check engine light came on. Code P0121 which indicates TPS isn't jiving with MAP sensor. Took it back up to 65 mph again and this time no issues. Is this normal following replacement of TPS as the main computer "learns"? Do I just reset the check engine light? If so, how do you do it? Appreciate any comments.

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Old 05-20-2013, 09:21 PM   #2
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Join Date: May 2012
Location: Bakersfield
Posts: 398
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You will need an OBD code reader to reset any codes, and for the bucking an no upshift and probably loss of power, this could be the result of possibly a bad wire or loose connection in the TPS circuit.
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