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GTECH Calibration
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P0720

Output Shaft Speed Sensor Circuit.

  • Generic
  • Powertrain
  • Generic code
  • Medium severity

How this code is built

P
SystemPowertrain
0
Defined bySAE, the same on every car
7
AreaTransmission
20
FaultThe specific fault in that area

What it means

P0720 is the generic SAE J2012 code for a fault in the output shaft speed sensor circuit. The transmission or powertrain control unit compares the output shaft speed signal with other inputs such as vehicle speed, turbine speed and engine speed. If the signal is missing, erratic or does not make sense for the gear selected, the code is set. The exact sensor location and the way the signal is checked vary by model and gearbox.

Symptoms

  • Gearbox warning light or malfunction indicator lamp on
  • Speedometer or rev-linked gauges erratic or reading zero
  • Harsh, delayed or flared gear changes
  • Gearbox stuck in one gear (limp mode)
  • No torque converter lock-up and higher fuel consumption
  • Cruise control not working

Possible causes

  • Faulty output shaft speed sensorlikely
  • Damaged, chafed or corroded wiring to the sensorlikely
  • Poor connector contact, water ingress or oil contamination at the sensor pluglikely
  • Metal debris on the sensor tip or a damaged reluctor or tone ringpossible
  • Low, dirty or incorrect transmission fluid affecting gearbox operation and sensor readingspossible
  • Internal gearbox fault causing real output shaft speed to disagree with other speed signalspossible
  • Fault in the transmission control unit or an outdated calibration known to affect this coderare

How to diagnose

  1. Read all stored codes and freeze frame data, and note any related speed sensor or vehicle speed codes
  2. Check transmission fluid level, condition and smell, following the manufacturer's procedure for your model
  3. Inspect the sensor, its wiring and connector for damage, leaks, corrosion and loose pins
  4. View live data for output shaft speed, vehicle speed and engine speed on a road test and look for dropouts or a signal that does not match
  5. Test the sensor circuit for supply, earth and signal, and check wiring for resistance and shorts, using the figures in the manufacturer data
  6. Test the sensor itself against the specified resistance or signal pattern, as the type (inductive or Hall effect) depends on the model
  7. Remove the sensor and inspect its tip for debris and the reluctor ring for damage
  8. Check for software updates or technical bulletins for your vehicle once the hardware has been proved good

How to fix

  • Replace the output shaft speed sensor if it fails testing
  • Repair or replace damaged wiring and clean or replace faulty connectors
  • Clean debris from the sensor and replace or repair a damaged reluctor ring
  • Correct the fluid level or change the fluid and filter as specified for the gearbox
  • Repair the gearbox internally if a mechanical fault is confirmed
  • Update the control unit calibration only where a bulletin identifies an outdated one as the cause

Can I keep driving?

Medium severity

The car can usually be driven short distances carefully, but expect limp mode and poor shifting. Get it checked soon, as continued driving with harsh or incorrect gear changes can damage the gearbox.

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

This code for other makes

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