P1771
Throttle Position Sensor Circuit Open To Transmission Control Module.
- Mazda
- Powertrain
- Manufacturer code
- Medium severity
How this code is built
- P
- SystemPowertrain
- 1
- Defined byThe manufacturer
- 7
- AreaTransmission
- 71
- FaultThe specific fault in that area
What it means
On Mazda models, P1771 means the transmission control module has detected an open circuit in the throttle position signal it uses to decide shift timing and line pressure. The module is seeing no valid signal, or a value outside the expected range, from the throttle position input. The exact signal source and wiring layout depend on the model and gearbox, so check the model-specific wiring diagram.
Symptoms
- Gearbox warning light or check engine light on
- Harsh, delayed or flared gear changes
- Gearbox stuck in one gear (limp mode)
- Poor or erratic shift points
- Reduced acceleration or hesitation
- Transmission fault stored together with engine throttle codes
Possible causes
- Damaged, chafed or broken wiring in the throttle position signal circuit to the transmission control modulelikely
- Corroded, loose or pushed-out pins at the throttle position sensor or transmission control module connectorlikely
- Faulty throttle position sensor with an open internal tracklikely
- Open circuit in the sensor's reference voltage or earth feedpossible
- Water ingress or heat damage to the harness or connectorspossible
- Faulty transmission control modulerare
How to diagnose
- Read all stored codes and freeze frame data, and note whether engine throttle or sensor codes are also present
- Check live data for throttle position on the scan tool and see whether it is steady, missing or jumps when the pedal is moved slowly
- Inspect the throttle position sensor, harness and connectors for damage, corrosion, water or looseness
- Wiggle-test the harness with live data on display to find an intermittent break
- Check the sensor's reference voltage, earth and signal wire at the connector against the manufacturer's specification
- With the battery disconnected, test the signal wire for continuity and for shorts between the sensor and the transmission control module using the wiring diagram
- Compare the sensor's output sweep through its range with the specification for the model
- Only after wiring and sensor are proven good, check the transmission control module's power, earth and connector, and consider the module itself
How to fix
- Repair or replace the damaged wiring section, using proper soldered or crimped and sealed joints
- Clean, re-seat or replace corroded or damaged connector terminals
- Replace the throttle position sensor if its output is open or erratic, and adjust or calibrate it if the model requires
- Restore the sensor's reference or earth supply by repairing the affected circuit
- Replace or reprogram the transmission control module only if it is confirmed faulty, following the manufacturer's procedure
Can I keep driving?
The car can usually be driven short distances, but limp mode and harsh shifting can stress the gearbox and make driving less predictable. Get it diagnosed soon and avoid heavy loads or towing until it is fixed.
Guide written by AI from the code's definition. Confirm with a diagnosis before replacing parts.