2004 Ford F-150 Slipping Reverse - Truck Trend Garage

Slippery Slope

Alex Steele
Jan 3, 2014
Question: My 2004 Ford F-150 started slipping in reverse. All forward gears are functioning properly. If I rev up the motor in reverse, it seems like it wants to go, but the light comes on and I get a P0720 code. I looked up the code and replaced the output speed sensor, and changed the fluid and filter.
Answer: DTC P0720 means the PCM detected a loss of output speed sensor input while in operation, which could be caused by a bad sensor. In your case, the loss of reverse is producing the DTC. The PCM sees you're in gear, foot on the throttle, but you're going nowhere. So it assumes the output speed sensor isn't working, but we know the actual cause is the transmission's output shaft isn't turning. The fact that you feel the truck wanting to move (slipping) strongly suggests an internal mechanical/hydraulic problem, not an external control issue. The fault may be in the reverse clutch assembly, low/reverse band, low reverse/servo, or an obstruction in a number of hydraulic circuits. The fact that it shifts fine in all forward gears tells us line pressure is good and the transmission pump is OK. A complete transmission overhaul is recommended most of the time. A specific fix will likely require removal and teardown of the transmission anyway.
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2015 Ford F-150 Specifications

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Fair Market Price $25,309
MSRP $25,800
Editors' Overall Rating
Mileage 18 City / 25 Highway
Engine 3.5L V6
Horse Power 283 hp @ 6,500 rpm
Torque 255 ft lb of torque @ 4,000 rpm
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Ford F 150

Fair Market Price
$25,309
Editors' Overall Rating
Basic Specifications
MSRP: $25,800
Mileage: 18 / 25
Engine: 3.5L V6
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