P0906 — Gate Select Position Circuit Low

What is the most common cause of P0906?

The most common causes are: open or shorted wiring in the circuit, faulty sensor or actuator of the affected circuit, blown fuse feeding the circuit.

What are the symptoms of P0906?

Drivers most often notice: the affected system operates intermittently or not at all, Check Engine Light on, increased fuel consumption in some cases, possible limp mode depending on the affected component.

Is it safe to drive with P0906?

In most cases the car remains drivable, possibly with reduced performance or a disabled auxiliary system. If symptoms include stalling, no-start or brake/steering warnings, treat it as urgent.

How much does it cost to fix P0906?

Replace the faulty sensor or actuator — $150–$500; Control module repair — $300–$1,000; Repair wiring or connectors — $80–$250. Exact cost depends on the root cause, your vehicle and local labor rates — a proper diagnosis is the cheapest first step.

Will P0906 clear itself?

Sometimes P0906 clears after a few drive cycles if the fault was intermittent — for example a loose connector or a tank of bad fuel. The underlying cause usually remains, so the code tends to return. Clear it once; if it comes back, diagnose rather than erase it repeatedly.

The transmission control module keeps a close eye on the gate select position sensor to know which gear range you've selected. When everything is working properly, this sensor sends a voltage signal back to the computer that stays within a specific window. P0906 triggers when that signal drops below the minimum expected voltage — essentially reading near ground level when it shouldn't be. This circuit-low condition tells the ECU that something is pulling the signal down, either through a wiring fault or a component failure.

In practice, this means the computer can't trust what the gate select position sensor is telling it. Since modern transmissions rely on accurate gear-position data for shift scheduling and line-pressure control, the module stores P0906 and illuminates the Check Engine light after confirming the fault across multiple drive cycles. The code itself doesn't tell you exactly which part failed — it just flags that the voltage reading has gone out of bounds. That's why systematic diagnosis matters: the cheapest repair is rarely the first one a parts-store clerk would suggest.

When the ECU sets P0906, it also captures freeze frame data — a snapshot of engine RPM, load, temperature, and vehicle speed at the moment the fault was detected. This information is invaluable because it points you toward the specific driving conditions that trigger the problem. If the code sets every time you reverse, for example, the issue likely involves circuitry that's only active in that gear range.

Common symptoms of P0906

• The transmission may shift roughly, slip, or fail to shift entirely until the fault clears
• Check Engine light remains illuminated on the dashboard
• Some vehicles enter limp mode, limiting the transmission to second or third gear only
• Fuel economy may increase due to improper shift timing
• The affected circuit — whether a sensor, actuator, or related wiring — operates intermittently or not at all
• In rare cases, the engine may stall or refuse to start if the gate select position data is critical to drivability

What causes P0906?

A circuit-low reading means voltage is being shunted to ground somewhere it shouldn't be. The most probable culprits, ranked roughly by frequency:

• Signal wire shorted to ground — often from insulation wear where the harness rubs against metal
• Failed gate select position sensor pulling the signal down internally
• Blown fuse or loss of supply voltage feeding the gate select position circuit
• Control module driver fault — the ECU itself may be unable to read the circuit correctly
• Open or high-resistance wiring creating a voltage drop that mimics a shorted condition
• Corroded, loose, or physically damaged connector at the sensor or TCM
• Poor ground connection at the component or module
• Faulty actuator or secondary device sharing the same circuit

How to diagnose P0906

Approach P0906 methodically — skip the parts store line and do the groundwork first:

1. Connect an OBD2 scanner, verify P0906 is stored, and record all freeze frame data. Note the RPM, load, temperature, and speed readings — these reproduce the exact conditions under which the fault occurred.
2. Pull all related codes. Codes in the P0900–P0905 range often point to the same circuit or shared power supply. Also search for TSBs (technical service bulletins) for your specific make, model, and year — many transmission-related P0xxx codes have published factory solutions or software updates.
3. Perform a thorough visual inspection of the wiring harness and connectors associated with the gate select position. Look for chafed insulation, broken strands inside wires, corrosion at the pins, and any signs of heat damage or previous repairs.
4. Check for proper supply voltage at the sensor connector first. Then measure resistance from the signal wire to ground — a reading near zero ohms confirms a direct short to ground in the harness.
5. Test reference voltage, ground integrity, and signal continuity at the component connector itself. Compare your readings against manufacturer specifications.
6. Wiggle the harness while monitoring live data on the scanner — any signal dropouts or interruptions point to a broken wire that only fails under movement.
7. Clear the code, drive through the conditions captured in the freeze frame data, and verify P0906 does not return. A code that won't come back means the fault was transient; a code that returns immediately confirms an active failure.

Repair options with pricing

Prices below reflect parts and labor at independent shop rates in the United States. Always confirm whether your vehicle requires dealer-level programming for control module work.

• Wiring or connector repair: $80–$250 — fixing a chafed wire, replacing terminals, or sealing a corroded connector is usually the lowest-cost fix and the most common root cause.
• Gate select position sensor or actuator replacement: $150–$500 — if testing confirms the component itself is dragging the signal low, replacement restores proper circuit behavior.
• Control module diagnosis and repair: $300–$1,000 — if the TCM or PCM driver circuit is at fault, repair may involve module replacement, reprogramming, or reflashing firmware.

How much does it cost to fix P0906?

Depending on which component actually failed, expect to spend between $80 and $1,000 total for P0906. The wide range reflects the difference between repairing a damaged connector versus replacing a transmission control module. An accurate diagnosis before purchasing parts is the single best way to keep costs down — the most expensive scenario is rarely where you should start, yet it's often what gets replaced first when the underlying wiring fault goes undetected.

Can you drive with P0906?

In most vehicles, P0906 allows continued driving — though you may notice degraded shift quality, reduced performance, or an auxiliary system that stops working. The Check Engine light is your reminder that something needs attention. Treat the situation as urgent if the transmission slips severely, the engine stalls, or you see brake or steering warnings alongside the code. Otherwise, schedule diagnosis within a reasonable timeframe rather than ignoring it indefinitely — the underlying fault rarely resolves on its own.

Related OBD2 codes

• P0900: Clutch Actuator Circuit/Open
• P0901: Clutch Actuator Circuit Range/Performance
• P0902: Clutch Actuator Circuit Low
• P0903: Clutch Actuator Circuit High
• P0904: Gate Select Position Circuit
• P0905: Gate Select Position Circuit Range/Performance