What Does P07A4 Mean?
Transmission friction element B is either underperforming or stuck in the off (released) position. The TCM has detected that element B is not engaging with adequate force when commanded, resulting in gear slippage or complete failure to achieve certain gear ratios. This may be a hydraulic delivery problem or a worn/failed friction element.
Safety Warning
The transmission may be unable to engage certain gears, limiting the vehicle's speed range and acceleration capability. If critical gears are affected, the vehicle may be essentially undrivable. Tow the vehicle if gear engagement is severely impaired.
Common Causes
30%
Apply piston or servo for element B stuck in released position
25%
Severely worn friction element B (insufficient material for engagement)
20%
Hydraulic blockage or restriction in element B apply circuit
15%
Pressure control solenoid not commanding adequate apply pressure
10%
Seal failure in element B clutch drum or apply circuit
Diagnostic Steps
1
Identify which gears utilize friction element B and test for engagement in those specific gears.
2
Monitor shaft speed sensors for complete slip (no ratio change) or partial slip (ratio deviation) in element B gears.
3
Perform a line pressure test in the gears where element B should be applied.
4
Check transmission fluid level and condition — critically low fluid can prevent element engagement.
5
If pressure is normal at the test port but element doesn't engage, suspect internal mechanical failure (stuck piston, worn friction material).
6
Transmission removal and disassembly is required for internal component inspection and repair.
Estimated Repair Cost
$500 - $4,000
Parts + labor, varies by vehicle and location
Transmission friction element B is either underperforming or stuck in the off (released) position. The TCM has detected that element B is not engaging with adequate force when commanded, resulting in gear slippage or complete failure to achieve certain gear ratios. This may be a hydraulic delivery p...
The most common cause of P07A4 (Transmission Friction Element "B" Performance/Stuck Off) is: Apply piston or servo for element B stuck in released position
Typical repair costs for P07A4 range from $500 to $4,000, depending on the vehicle, location, and whether you do it yourself or go to a shop.
The transmission may be unable to engage certain gears, limiting the vehicle's speed range and acceleration capability. If critical gears are affected, the vehicle may be essentially undrivable. Tow the vehicle if gear engagement is severely impaired.
Start by connecting an OBD2 scanner to read the code and any freeze frame data. Then follow the diagnostic steps specific to P07A4 to identify the root cause.
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Quick Info
Category
Powertrain
System
Automatic Transmission
Difficulty
Type
Generic (SAE)
Recommended Tools
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