What Does P071A Mean?
The transmission mode switch A circuit has a general malfunction. This switch allows the driver to select different transmission operating modes (such as Sport, Eco, Winter, or Manual). The TCM is not receiving a valid signal from the switch. The driver may find that the mode selection has no effect or that the transmission defaults to a standard operating mode.
Common Causes
35%
Faulty transmission mode switch/selector
30%
Damaged wiring or connector between the mode switch and TCM
15%
Corroded or stuck switch contacts (liquid spill into center console)
10%
TCM not recognizing the mode switch signal due to software or calibration
10%
Blown fuse or relay in the mode switch circuit
Diagnostic Steps
1
Use live data to monitor the mode switch PID while cycling through all mode positions. The scan tool should reflect each mode change. No change confirms a circuit or switch fault.
2
Inspect the mode switch connector (typically located on the center console or gear shifter housing) for corrosion, spill damage, or loose connections.
3
Check for power and ground at the switch connector with KOEO. Verify the reference voltage (5V or 12V depending on design) is present.
4
Measure the switch contact resistance in each position. Compare to manufacturer's specification — each mode should produce a distinct resistance or voltage value.
5
Verify the fuse supplying the mode switch circuit is intact. Check the wiring continuity from the switch to the TCM.
Estimated Repair Cost
$50 - $350
Parts + labor, varies by vehicle and location
The transmission mode switch A circuit has a general malfunction. This switch allows the driver to select different transmission operating modes (such as Sport, Eco, Winter, or Manual). The TCM is not receiving a valid signal from the switch. The driver may find that the mode selection has no effect...
The most common cause of P071A (Transmission Mode Switch "A" Circuit) is: Faulty transmission mode switch/selector
Typical repair costs for P071A range from $50 to $350, depending on the vehicle, location, and whether you do it yourself or go to a shop.
Safe to drive. The transmission will operate in its default mode and shift normally. The only effect is the loss of alternate mode selections (Sport, Eco, etc.). This is a convenience issue and can be repaired at your next service appointment.
Start by connecting an OBD2 scanner to read the code and any freeze frame data. Then follow the diagnostic steps specific to P071A to identify the root cause.
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Quick Info
Category
Powertrain
System
Transmission
Difficulty
Type
Generic (SAE)
Recommended Tools
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