Low, degraded or contaminated transmission fluid causing low clutch apply pressure; Worn or burnt friction plates in the clutch or brake pack for element F; Faulty shift solenoid or pressure control solenoid for element F, sticking or failing electrically; Valve body wear, sticking valves or internal hydraulic leaks, including worn seals or pistons; Wiring or connector fault between the transmission control module and the solenoid or internal harness; Blocked fluid filter or restricted fluid passages reducing pressure; Faulty transmission control module or outdated software calibration, where a manufacturer update is known for this fault.

P07AC

Transmission Friction Element F Performance/Stuck Off.

Generic
Powertrain
Generic code
High severity

How this code is built

P: SystemPowertrain
0: Defined bySAE, the same on every car
7: AreaTransmission
AC: FaultThe specific fault in that area

What it means

P07AC is a generic powertrain code meaning the transmission control module has detected that friction element F (a clutch or brake pack, depending on the transmission design) is not engaging when commanded, so it is performing poorly or is stuck off. The module saw a mismatch between the expected gear ratio or speed relationship and the actual input and output shaft speeds while that element was meant to be applied. Which physical clutch or brake is 'element F' varies by transmission, so the exact component must be confirmed from the manufacturer data.

Symptoms

Gearbox flare or slip, with engine revs rising without matching acceleration in certain gears
Harsh, delayed or missed shifts into the gear that uses element F
Gearbox defaulting to limp mode, locked in a single gear
Loss of drive or no engagement in a particular gear or in reverse
Gearbox warning light or malfunction message on the dash
Poor acceleration or reduced performance

Possible causes

Low, degraded or contaminated transmission fluid causing low clutch apply pressurelikely
Worn or burnt friction plates in the clutch or brake pack for element Flikely
Faulty shift solenoid or pressure control solenoid for element F, sticking or failing electricallylikely
Valve body wear, sticking valves or internal hydraulic leaks, including worn seals or pistonspossible
Wiring or connector fault between the transmission control module and the solenoid or internal harnesspossible
Blocked fluid filter or restricted fluid passages reducing pressurepossible
Faulty transmission control module or outdated software calibration, where a manufacturer update is known for this faultrare

How to diagnose

Read all stored codes and freeze frame data, noting gear, fluid temperature, speed and load when the fault set, and check for other transmission or speed sensor codes
Check the transmission fluid level and condition (colour, smell, debris) following the procedure for that model, as some transmissions are sealed and need specific temperature checks
Look up the manufacturer data to identify which clutch or brake is element F and which gears use it
Inspect the transmission wiring, connectors and external harness for damage, corrosion, fluid ingress or chafing
Check live data for input and output shaft speeds, gear ratio and slip, and solenoid commanded versus actual pressure or current
Test the solenoid circuit resistance and operation against specification, if accessible externally
Perform any manufacturer-specified pressure or clutch adaptation tests, and check for applicable software updates or technical bulletins
If the fault persists, inspect the valve body and clutch pack internally after the pan is dropped, checking for debris and wear

How to fix

Correct the fluid level or replace degraded fluid and filter using the specified fluid type
Repair or replace damaged wiring, connectors or the internal harness
Replace the faulty solenoid or valve body components as found
Overhaul or replace the worn clutch or brake pack, seals and pistons for element F
Update the transmission control module software only where the manufacturer lists it as a fix, and carry out the adaptation reset afterwards
Replace the transmission control module only after other causes are ruled out and it is confirmed faulty

Can I keep driving?

High severity

Avoid driving beyond what is needed, as slipping clutches can quickly cause heavy internal transmission damage. If the car is in limp mode or slipping, stop driving it and have it inspected or recovered.

Guide written by AI from the code's definition. Confirm with a diagnosis before replacing parts.