P0816 code meaning
Downshift Switch Circuit
What P0816 means
Tap-up and tap-down switches let the driver choose gears on an automatic (selector gate, buttons or paddles). GM, Ford and Saab all treat a shift request that appears where it is impossible – in park or neutral, at Ford also reverse – or that stays on implausibly long as a stuck switch. P0816 is the mirror of P0815 for the downshift switch. GM's 2025 table sets it when 'tap down' stays on for more than 1 s (100 ms raster, over 9 V), the 2018 hybrid table after 2 s in P/N or 655 s in drive, type C without MIL; Saab's 9-4X after 1 s in P/N or 10 minutes in a drive range; Ford's SelectShift when the switch is closed in P, R or N, without MIL. On selectors with a resistor network a short to positive in the downshift branch sets P0816. Manual shifting is disabled, automatic operation stays normal.
P0816 at a glance
- Check engine lightUsually not
- Emissions testNot an emissions code
- Limp modeNot expected
- Repair difficultyMedium
- Typical labor0.5 to 2.5 hours
- Clears after repairWhen cleared with a scanner
Symptoms of P0816
- Manual down shifting not working
- Transmission stays in the normal automatic mode
- No check engine lamp
Common causes of P0816
- Most likelyDownshift switch or paddle sticking or faulty
- PossibleSignal wire shorted to positive
- PossibleSelector assembly faulty
- Less likelyBody or transmission module
Check the most likely causes first. Replacing parts by guesswork is the most expensive way to clear a code.
Parts involved
Tap shift switchGear selectorSwitch wiringTransmission control module
What each part of P0816 means
| P | Powertrain system: engine, fuel system, ignition, emissions and transmission. |
| 0 | Generic code: it means the same on every make (SAE standard). |
| 8 | Area: transmission. |
| 16 | The exact fault in that area. |
What to do next
- Note P0816 and any other codes stored with it: several codes together often point to one cause.
- Check for loose connectors and damaged wiring around the parts the code names.
- Check open recalls for your car: some faults are fixed for free by the dealer. Enter your VIN.
- Clear the code only after the repair. If it comes back, the fault is still there.
Buying a used car? Scan it for stored codes before you pay. A recently cleared memory can hide a problem.
Questions about P0816
What does P0816 mean?
P0816 means "Downshift Switch Circuit". Tap-up and tap-down switches let the driver choose gears on an automatic (selector gate, buttons or paddles). It is a generic code, so it means the same on every make.
Is it safe to drive with P0816?
P0816 does not normally turn on the check engine light by itself. Watch for the symptoms above and have it checked soon.
Will P0816 fail an emissions test?
P0816 is not an emissions code, so on its own it usually does not fail an emissions test. Other stored codes or a lit check engine light still can.
How hard is P0816 to fix?
Difficulty: medium. A typical repair takes 0.5 to 2.5 hours of work. This is a job for a workshop.
Will P0816 clear itself after the repair?
Clear the code with a scanner after the repair. If the fault is fixed, it does not come back.