P0906Generic code

P0906 Code: Gate Select Position Circuit Low

The P0906 code means the gate select position sensor signal is below its minimum value. The main effect is that the transmission does not know where its mechanism is. Look for a signal wire shorted to ground or a missing reference voltage.

Severity
High
Can I keep driving?
Yes, but with caution
Estimated cost
$60 to $800
Difficulty
Medium
System
Transmission
Applies to
All OBD2 vehicles

Updated Reviewed by Renzo Chacca

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What the P0906 code means

Automated manual transmissions (Opel Easytronic, Fiat Dualogic, Toyota MMT, BMW SMG, Ford Durashift, Volkswagen ASG) and many dual clutch transmissions use electric or hydraulic actuators to disengage the clutch, to choose the gear plane (select) and to engage the gear (shift). The transmission computer watches every actuator with position sensors. The select sensor reports which plane the mechanism is in.

The sensor gets a 5 volt reference and a ground from the computer and sends back a signal between about 0.5 and 4.5 volts. A low signal, which is what the P0906 code reports, usually comes from a signal wire shorted to ground or from a missing reference voltage.

If its signal fails, the computer does not know which plane is selected and blocks the shifts. After any repair of these components you must run the transmission relearn procedures with a scan tool (clutch touch point, select and shift positions). Without them the transmission will not work properly.

To confirm the fault, unplug the component with the key on and watch the reading or the code. If the value jumps to the opposite extreme, the wiring is good and the component is the one pulling the signal to ground. If nothing changes, look for the short in the wire, starting where the harness rubs against the engine, the chassis or the exhaust.

P0906 code symptoms

  • Check engine light on.
  • The transmission does not recognize the position of its mechanism.
  • The transmission does not go into gear or stays in neutral.

Likely causes of the P0906 code

  1. Signal wire shorted to ground because the harness rubs against the engine, the chassis or a bracket.
  2. Shorted reference supply. If several sensors fail at once, suspect the shared reference.
  3. Damaged sensor with an internal short.
  4. Connector with water or corrosion, which creates a path to ground.

How to diagnose the P0906 code step by step

  1. Read the sensor value on the scan tool and compare it with what you expect.
  2. Inspect the connector for corrosion, water or loose pins.
  3. Check supply and ground with the key on: the reference should be correct and the ground voltage drop under 0.1 volts.
  4. Measure the signal with the connector attached and see whether it changes with the condition.
  5. Do a wiring wiggle test with the scan tool in graphing mode.
  6. Check the continuity of each wire to the computer (under 1 ohm).
  7. Run the transmission relearn procedures after the repair.

How to fix the P0906 code

  • Repair the connector or the wiring.
  • Replace the sensor if the tests confirm it is bad.
  • Correct the real condition if one exists.
  • Clear the codes and verify with a road test.

Technical reference data

  • 5 volt reference, ground and a signal of 0.5 to 4.5 volts (or a contactless Hall effect sensor).
  • Approximate values only: check the manufacturer data for your vehicle.

Brand-specific notes

This code is very common on automated manual transmissions. On many hydraulic systems the actuator fluid is a specific type and the reservoir should be checked regularly.

P0906 on Opel

Very common on the Opel Easytronic.

P0906 on Fiat

Very common on the Fiat Dualogic.

P0906 on Toyota

Very common on the Toyota MMT.

P0906 on Smart

Seen on Smart vehicles with an automated manual transmission.

P0906 on BMW

Very common on the BMW SMG.

Frequently asked questions about P0906

Can I drive with a P0906 code?
With caution. The transmission can be left without gears.
Do I have to replace the sensor?
Only if the tests confirm it. The connector and the wiring fail just as often as the sensor does.
What does the gate select position sensor do?
Automated manual transmissions (Opel Easytronic, Fiat Dualogic, Toyota MMT, BMW SMG, Ford Durashift, Volkswagen ASG) and many dual clutch units use electric or hydraulic actuators to release the clutch, select the gear plane and engage the gear. The computer watches each actuator with position sensors. The select sensor reports which plane the mechanism is in.
How much does it cost to fix P0906?
As a rough guide, between $60 and $800. A wire repair is at the low end, and a new sensor with the relearn procedures costs more.
What does the P0906 code mean?
The P0906 code is a generic OBD2 code that means the gate select position sensor signal is below its minimum value.
Will a P0906 code clear itself?
Only if the cause was a temporary short. A chafed wire or a wet connector will bring it back.
What is the most common cause of P0906?
A signal wire shorted to ground where the harness rubs. A shorted reference supply and a damaged sensor follow.

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