P0816 low

Downshift Switch Circuit

The P0816 code means the vehicle's onboard diagnostic system has detected: Downshift Switch Circuit. This is a low severity code.

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Keep driving?: Yes, but fix soon
DIY difficulty: easy
Estimated cost: $100 - $600 (parts and labor)

Check Your Fluid First

ANCEL AD310 OBD-II Scanner

Read and clear transmission codes. Many trans codes are caused by low or burnt fluid -- check level and color before assuming the worst.

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Read Transmission Codes

LAUNCH CRP123X (Reads All Systems)

Basic scanners only read engine codes. This reads transmission, ABS, and airbag too.

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Common Symptoms

Check Engine Light illuminated
Manual downshift paddle or button does not work
Unable to manually downshift in sport mode
Transmission only operates in automatic mode

Probable Causes (Ranked by Likelihood)

Faulty downshift paddle or switch Very High
Wiring fault in downshift switch circuit High
Clock spring failure affecting paddle shifter signals Moderate
TCM input circuit failure Low

Step-by-Step Diagnostic Procedure

Monitor downshift switch input with a scan tool while pressing the paddle
Check the clock spring connector at the steering column
Test continuity of the downshift circuit from switch to TCM
Inspect for corrosion at the steering wheel electrical connector

Frequently Asked Questions

Is P0816 related to P0815?

Yes, P0815 is for the upshift switch and P0816 is for the downshift switch. If both codes appear together, the clock spring or shared wiring is a likely cause.

Does P0816 affect normal driving?

No, the transmission will shift normally in automatic mode. Only the manual downshift feature is disabled.

Can I fix a paddle shifter myself?

If the paddle switch itself is faulty, it can often be replaced by removing the steering wheel trim. However, if the clock spring is the issue, airbag safety precautions are required.