P07A5
Transmission Friction Element B Stuck On.
- Generic
- Powertrain
- Generic code
- High severity
How this code is built
- P
- SystemPowertrain
- 0
- Defined bySAE, the same on every car
- 7
- AreaTransmission
- A5
- FaultThe specific fault in that area
What it means
P07A5 is a generic powertrain code meaning the transmission control module has detected that friction element B, a clutch or brake pack inside the automatic gearbox, is stuck on (engaged when it should be released). It is usually set when the measured gear ratio or input and output speed relationship does not match the gear commanded, or when element B is applied in a gear where it should be off. Which physical clutch or brake 'B' refers to depends on the gearbox design, so check the manufacturer's information for the specific model.
Symptoms
- Gearbox warning light or malfunction indicator lamp on
- Transmission stuck in one gear or in limp mode
- Harsh, delayed or flared gear changes
- Engine braking, binding or the car feeling held back when pulling away or coasting
- Engine stalling or struggling when selecting drive or reverse
- Poor acceleration or reduced top speed
Possible causes
- Shift solenoid or pressure control solenoid for element B sticking or failing so that it keeps the element appliedlikely
- Contaminated, degraded or incorrect level of transmission fluid causing valve or solenoid stickinglikely
- Valve body wear, sticking valves or blocked fluid passages keeping hydraulic pressure on element Bpossible
- Wiring or connector fault on the solenoid circuit, or an internal harness fault in the gearboxpossible
- Faulty input or output speed sensor giving a false slip or ratio readingpossible
- Mechanically failed clutch or brake pack, such as burnt, fused or collapsed plates or a seized pistonpossible
- Outdated or faulty transmission control module software, or a failed modulerare
How to diagnose
- Read all stored and pending codes plus freeze frame data, noting gear commanded, gear ratio, temperature and speed when the fault set
- Check the transmission fluid level and condition (colour, smell, debris) using the manufacturer's procedure, as the method varies by model
- Inspect the gearbox wiring, connectors and external harness for damage, corrosion, fluid ingress and chafing
- Check live data for input speed, output speed, calculated ratio and solenoid commanded versus actual current in each gear
- Test the speed sensors and solenoid circuit resistance and signals against manufacturer specifications
- Check for related codes such as other ratio, slip or solenoid faults to help identify which element B is on this gearbox
- Look up manufacturer service bulletins and software updates for the specific model and gearbox
- Carry out a line pressure test and, if needed, inspect the valve body and clutch packs
How to fix
- Replace the faulty shift or pressure control solenoid for element B
- Service the transmission with the correct fluid and filter, and correct the level, if the fluid is contaminated or low
- Clean, repair or replace the valve body if valves are sticking or worn
- Repair or replace damaged wiring, connectors or the internal gearbox harness
- Replace the faulty speed sensor
- Overhaul or replace the gearbox if clutch or brake pack components are mechanically damaged, and update the control module software only where a known fault calls for it
Can I keep driving?
Avoid driving the car if it is stuck in a gear, binding or in limp mode, as continued use can cause severe and costly gearbox damage and may be unsafe. If it must be moved, keep it to a short, slow, gentle trip to a workshop.
Guide written by AI from the code's definition. Confirm with a diagnosis before replacing parts.