P073B
Stuck in Gear 6.
- Generic
- Powertrain
- Generic code
- High severity
How this code is built
- P
- SystemPowertrain
- 0
- Defined bySAE, the same on every car
- 7
- AreaTransmission
- 3B
- FaultThe specific fault in that area
What it means
P073B means the transmission control unit has detected that the gearbox is stuck in sixth gear, or will not leave it, when a different gear has been requested. It sets when the measured gear ratio, from input and output speed signals, or the gear position feedback stays at sixth while the commanded gear is different. How it is detected and what usually causes it depends on the transmission type (conventional automatic, dual-clutch or automated manual) and the model.
Symptoms
- Car stays in sixth gear at low speed and feels sluggish or struggles to pull away
- Poor acceleration or labouring when slowing down or climbing hills
- Gearbox warning light or malfunction message on the dash
- Transmission goes into limp mode or refuses to change gear
- Harsh, delayed or no downshifts
- Engine may stall or judder when stopping if the gearbox cannot drop out of sixth
Possible causes
- Faulty shift solenoid or actuator sticking in the sixth-gear positionlikely
- Low, degraded or contaminated transmission fluid affecting hydraulic pressure or clutch operationlikely
- Faulty input or output speed sensor, or gear position sensor, giving incorrect readingspossible
- Wiring or connector faults (chafing, corrosion, poor pin tension) in the transmission harnesspossible
- Valve body wear or blockage, or mechanical fault in a selector fork, clutch pack or synchroniserpossible
- Faulty transmission control unit or outdated software calibration where the manufacturer has issued a known updaterare
How to diagnose
- Read all stored and pending codes and the freeze frame data, noting speed, commanded gear, actual gear and fluid temperature when the fault set
- Check for other transmission, speed sensor or engine codes, as these may point to the root cause
- Check the transmission fluid level and condition where the design allows, and compare with the manufacturer's procedure (some units are sealed and need a specific temperature check)
- Inspect the transmission wiring harness and connectors for damage, leaks, corrosion and poor connections
- Use live data to compare input speed, output speed, commanded gear and actual gear while driving or on a test drive, and check the sensor signals are plausible
- Test the speed and position sensors and their supply, ground and signal circuits against the manufacturer's specifications
- Check the manufacturer's service information for software updates or known faults for that model and gearbox
- Perform solenoid and actuator tests with the diagnostic scan tool if supported, and check line pressure where the procedure allows
How to fix
- Correct the fluid level or change the fluid and filter using the correct specification, if it is low or degraded and the design allows
- Repair or replace damaged wiring, connectors or terminals in the transmission harness
- Replace a faulty speed sensor or gear position sensor
- Replace a faulty shift solenoid or actuator, or overhaul or replace the valve body if it is worn or blocked
- Repair internal mechanical faults in the gearbox, such as selector forks or clutches, once confirmed
- Update or replace the transmission control unit calibration only where an outdated or faulty calibration is a known cause for that model
Can I keep driving?
Limit driving, as the gearbox may be stuck in a high gear and could suffer clutch or further internal damage, and the car may be difficult to pull away or unsafe in traffic. If it is in limp mode or struggling to move, stop and have it recovered rather than continue.
Guide written by AI from the code's definition. Confirm with a diagnosis before replacing parts.