What Does P0906 Mean?
The TCM has detected that the gate select position sensor circuit voltage is below the minimum expected threshold. This typically indicates a short to ground in the sensor circuit, a failed sensor with low output, or an open in the 5V reference supply to the sensor. The TCM cannot accurately determine the left/right gate position for gear selection.
Safety Warning
The transmission cannot reliably select the correct gear gate. The vehicle may enter a limp-home mode or refuse to shift. Do not drive until repaired.
Common Causes
35%
Gate select position sensor internal failure producing low output
30%
Short to ground in signal wire between sensor and TCM
20%
Open or high resistance in 5V reference supply wire to sensor
15%
Corroded ground connection causing voltage offset
Diagnostic Steps
1
Step 1: Measure the gate select sensor output voltage at the sensor connector with key on engine off — if below 0.3V, the signal is shorted low.
2
Step 2: Disconnect the sensor and measure 5V reference at the harness connector — absence of 5V indicates an open supply wire or TCM reference circuit fault.
3
Step 3: With the sensor disconnected, check the signal wire for shorts to ground — measure resistance from the signal pin to chassis ground; should read OL (open).
4
Step 4: Inspect the wiring harness for physical damage, especially where it routes near the transmission case or exhaust heat shields.
5
Step 5: If wiring checks good, replace the gate select position sensor and verify the code clears after a road test adaptation procedure.
Estimated Repair Cost
$120 - $650
Parts + labor, varies by vehicle and location
The TCM has detected that the gate select position sensor circuit voltage is below the minimum expected threshold. This typically indicates a short to ground in the sensor circuit, a failed sensor with low output, or an open in the 5V reference supply to the sensor. The TCM cannot accurately determi...
The most common cause of P0906 (Gate Select Position Circuit Low) is: Gate select position sensor internal failure producing low output
Typical repair costs for P0906 range from $120 to $650, depending on the vehicle, location, and whether you do it yourself or go to a shop.
The transmission cannot reliably select the correct gear gate. The vehicle may enter a limp-home mode or refuse to shift. Do not drive until repaired.
Start by connecting an OBD2 scanner to read the code and any freeze frame data. Then follow the diagnostic steps specific to P0906 to identify the root cause.
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Quick Info
Category
Powertrain
System
Automated Manual Transmission (Shift Control)
Difficulty
Type
Generic (SAE)
Recommended Tools
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