P0510: Closed Throttle Position Switch

Older engines with a mechanical throttle have a separate idle contact on the throttle or the combined throttle position sensor (Bosch Motronic throttle switch, Nissan and Toyota sensors with idle switch). The module uses it to recognise idle – for idle control, fuel cut-off on overrun and idle ignition timing – and as a substitute if the position sensor fails. P0510 flags an implausible switch: closed with the throttle open, or open at idle. Manufacturer thresholds were not found in accessible documents; with electronic throttle the switch no longer exists.

High severity. Can I keep driving?Be careful: the car may suddenly lose power. If it goes into limp mode, get off the highway and calmly make your way to a repair shop.

Symptoms

Idle too high or fluctuating
Engine stalls when coasting
No fuel cut-off on overrun (higher consumption)

Most likely causes

Idle switch or throttle sensor misadjusted
Switch contacts worn, dirty or corroded
Wire or connector open or shorted
Throttle not closing (deposits, sticking cable, stop misadjusted)
Value not relearned after replacement

What to check, in order

Start with the simplest. You can tick off each step.

Check the pedal and throttle connectors
Use live data to confirm that both sensors rise smoothly and consistently
Clean the throttle if it has carbon buildup
Run the relearn procedure with the scanner if the manufacturer requires it
Replace the part identified by the diagnosis

Good to know

Repair difficulty: medium
It affects emissions.

What each character of P0510 means

P: Powertrain: engine and transmission
0: Generic code: same on every make
5: Speed and idle
10: Specific fault in that system

Frequently asked questions

Can I keep driving with code P0510?

Be careful: the car may suddenly lose power. If it goes into limp mode, get off the highway and calmly make your way to a repair shop.

What causes code P0510?

The most common causes are: idle switch or throttle sensor misadjusted; switch contacts worn, dirty or corroded; wire or connector open or shorted.

Related codes

Sources

Values and procedures vary by manufacturer. If it affects brakes, steering, fuel or high voltage, see a professional. Updated: 2026-11-04. How we build these pages.