P0816 Low Generic / SAE

P0816: Downshift Switch Circuit

What to do

Manual downshift requests are ignored; automatic shifting is unaffected. If the horn or steering wheel audio buttons have also become unreliable, mention it — that combination points at one part behind the steering wheel rather than several switches.

What this code means

A circuit fault in the switch requesting a manual downshift, mirroring P0815. Automatic operation is unaffected.

Where both this and P0815 are stored together, look at what the two circuits share rather than at two switches. On a steering wheel installation that shared element is usually the clockspring — the coiled ribbon cable that carries every steering wheel signal across the rotating joint — and a failing one takes out paddles, horn and audio controls in various combinations.

Likely causes

Start here

Faulty manual shift switch · easy
Faulty clock spring in steering wheel · moderate

Less common

Corroded or loose connector · easy
Open circuit in switch wiring · moderate

Symptoms

Components involved

Information, not instruction

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Have anything you intend to act on checked by a trained person against the manufacturer's own procedure for your vehicle. Nothing here replaces that procedure.

Community experience

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