OBD-II Generic Error Code P0815: Upshift Switch Circuit – How to Fix It

Medium 30 minutes to 1 hour Medium Severity Verified June 2026
Error Code
P0815
Brand
OBD-II Generic
Product Type
automotive
Severity
Medium
DIY Difficulty
Medium
Estimated Fix Time
30 minutes to 1 hour
Error code P0815 indicates a problem with the upshift switch circuit in your vehicle's transmission shift system. This switch signals the transmission control module (TCM) when the driver requests an upshift. A faulty switch, wiring issue, or TCM problem can trigger this code. Ignoring it may lead to poor shifting performance or limp mode.
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Tools You'll Need

How to Fix Error Code P0815

  1. Check for Additional Codes

  2. Inspect the Upshift Switch Wiring and Connector

    Disconnect the battery before working on electrical components.
  3. Test the Upshift Switch with a Multimeter

  4. Check for Short or Open in the Circuit

  5. Test the TCM Output (Advanced)

    Backprobing risks damaging connectors; use proper tools.

Parts You May Need

Wiring harness/connector
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Wiring harness/connector
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Wiring harness/connector
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Wiring harness/connector
Check Price on Amazon
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When to Call a Professional

If you've checked the switch and wiring but the code returns, or if you're uncomfortable testing TCM signals, take your vehicle to a qualified mechanic. TCM replacement requires reprogramming.

Frequently Asked Questions

What does error code P0815 mean?
P0815 indicates a fault in the upshift switch circuit, which tells the transmission control module when the driver wants to shift to a higher gear.
Can I drive with a P0815 code?
Yes, but it may cause poor shifting or limp mode. It's best to diagnose and fix it promptly to avoid transmission damage.
Is the upshift switch the same as the shifter?
The upshift switch is typically a button or part of the shift lever (e.g., on the steering wheel or gearshift) used for manual shifting.