Damaged, chafed or shorted sensor wiring to earth, or an open circuit; Corroded, loose or contaminated connector at the sensor or transmission control unit; Failed intermediate shaft speed sensor C; Fluid contamination or metal debris on the sensor or its target; Low supply or reference voltage to the sensor from a wiring fault or a problem with the supply; Faulty transmission control unit or internal transmission harness (mechatronic unit, where fitted); Damaged sensor target wheel or mechanical shaft fault.

P07C9

Intermediate Shaft Speed Sensor C Circuit Low.

Generic
Powertrain
Generic code
Medium severity

How this code is built

P: SystemPowertrain
0: Defined bySAE, the same on every car
7: AreaTransmission
C9: FaultThe specific fault in that area

What it means

P07C9 means the transmission control unit has seen a low voltage or signal level in the circuit of intermediate shaft speed sensor C. Which shaft or sensor is 'C' depends on the transmission design, so check the manufacturer's data for the vehicle. The fault sets when the signal stays below the expected range, which points to a short to earth, an open circuit or a failed sensor.

Symptoms

Gearbox warning light or malfunction indicator lamp on
Transmission in limp-home mode, often stuck in one gear
Harsh, delayed or flared gear changes
Erratic or non-working speedometer or gear indicator
Reduced power or refusal to shift into some gears
Poor fuel economy

Possible causes

Damaged, chafed or shorted sensor wiring to earth, or an open circuitlikely
Corroded, loose or contaminated connector at the sensor or transmission control unitlikely
Failed intermediate shaft speed sensor Clikely
Fluid contamination or metal debris on the sensor or its targetpossible
Low supply or reference voltage to the sensor from a wiring fault or a problem with the supplypossible
Faulty transmission control unit or internal transmission harness (mechatronic unit, where fitted)rare
Damaged sensor target wheel or mechanical shaft faultrare

How to diagnose

Read all stored and pending codes with freeze frame data, and note any other speed sensor or communication codes.
Check transmission fluid level and condition against the manufacturer's procedure, looking for contamination or debris.
Inspect the sensor, wiring and connectors for chafing, heat damage, leaks and corrosion, and check the connector pins for tightness.
Look up the manufacturer's data for the location and wiring of sensor C on this transmission, as it varies by model.
Check the sensor supply, signal and earth with a multimeter or oscilloscope with the connector unplugged and plugged in.
Test the circuit for short to earth and open circuit, and compare the sensor resistance with the specification.
View live data for the sensor signal while the car is driven or the shafts are turning, and compare it with other speed sensors.
Check the sensor tip and target for metal debris, damage or excess clearance if it can be reached.

How to fix

Repair or replace damaged wiring and fix any short to earth or open circuit.
Clean or replace corroded or loose connectors and terminals.
Replace the intermediate shaft speed sensor C if it fails testing.
Correct fluid level or condition, and clean debris from the sensor area, as the manufacturer specifies.
Repair the sensor supply fault or replace the faulty control unit or internal harness once confirmed by testing.
Clear the code after repair and road test to confirm it does not return.

Can I keep driving?

Medium severity

The car can usually be driven carefully a short distance, but limp mode may leave it stuck in one gear and further driving risks transmission damage. Get it checked soon and avoid heavy loads or towing.

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