P07B1

What it means

P07B1 means the transmission control module has detected that friction element H, one of the clutches or brakes used to select gears, is engaged when it has not been commanded on. The module sees this from speed sensor readings, gear ratio checks or slip monitoring that do not match the commanded gear. Which clutch or brake is 'H' depends on the transmission design, so the exact element varies by model.

Symptoms

• Gearbox warning light or malfunction indicator lamp on
• Car stuck in one gear or in limp mode
• Harsh, delayed or flared gear changes
• Engine braking, shudder or the car feeling held back when pulling away
• Engine stalling or nearly stalling when stopping or selecting a gear
• Poor fuel economy and reduced performance

Possible causes

• Shift solenoid or pressure control solenoid sticking or stuck open for element Hlikely
• Contaminated, degraded or incorrect level of transmission fluid affecting valve operationlikely
• Valve body sticking valve or worn bores causing unwanted hydraulic pressure to element Hpossible
• Wiring or connector fault on the solenoid circuit, such as a short to power or chafed loompossible
• Faulty input, output or turbine speed sensor giving a false ratio readingpossible
• Mechanically damaged or burnt clutch or brake pack that cannot releaserare
• Outdated transmission control software where a manufacturer update is known to address the faultrare

How to diagnose

1. Read all stored and pending codes and the freeze frame data, noting gear, temperature, speed and fluid temperature when it set
2. Check for related codes such as solenoid circuit, speed sensor or gear ratio faults, and diagnose those first
3. Check the transmission fluid level, condition and smell, following the procedure for that model as some are sealed and need a set temperature
4. Inspect the transmission wiring, connectors and any external harness for damage, water ingress, corrosion or chafing
5. Check live data for input, output and turbine speeds and compare against the commanded gear to see whether slip or binding is occurring
6. Test the solenoid circuit for resistance, supply and control signals against the manufacturer's specification
7. Perform the manufacturer's hydraulic or pressure tests where available, and check for a software update or technical bulletin for the model
8. Inspect the valve body and clutch packs only if the above points to an internal fault

How to fix

• Correct the fluid level or replace degraded fluid and filter using the specified type
• Repair or replace damaged wiring, terminals or connectors on the transmission circuit
• Replace the faulty solenoid or speed sensor once testing confirms it
• Clean, repair or replace the valve body if valves are sticking
• Overhaul or replace the transmission if the clutch or brake pack is mechanically damaged
• Apply an updated transmission control calibration only where the manufacturer lists it as the fix for this fault

Can I keep driving?

Nearby codes

• P07B0GenericTransmission Friction Element H Performance/Stuck Off
• P07B2GenericTransmission Park Position Sensor/Switch A Circuit/Open