What it means
The dedicated closed-throttle switch (or closed-throttle bit on the TPS) does not behave as expected - either it never activates, never deactivates, or shows incoherent state against TPS voltage and engine load. Used by older systems for fuel-cutoff and idle recognition.
At a glance
- Usually lights the check-engine light
How it works
The closed-throttle switch tells the engine control module when the throttle is at its idle position; some systems use a separate switch, while others derive the signal from the throttle position sensor. P0510 sets when the module does not see the expected change in that idle signal or finds it inconsistent with throttle position and engine load.
Common causes
Most likely first.
- Switch out of adjustment or worn
- TPS idle voltage offset
Symptoms
- Check engine light on
- Reduced throttle response, possible limp mode
- Hesitation or surging
- Idle too high or too low
How to diagnose it
- Check freeze-frame data and live throttle-position and closed-throttle status to see whether the switch signal changes as the accelerator is released and pressed.
- With the engine off, inspect the throttle linkage or electronic throttle mechanism for binding and check the switch and connector for looseness, damage, or contamination.
- Compare the closed-throttle switch state with throttle position sensor readings through the pedal's range to identify a stuck or misaligned idle indication.
- Check the switch or TPS wiring for opens, shorts, poor grounds, and damaged terminals, and test continuity or signal changes using the manufacturer's procedure.
- If the wiring is sound, check and adjust the switch position or TPS setup only as specified by the manufacturer, then confirm the idle signal changes consistently.
Common fixes
- Repair a loose or damaged connector or wiring at the closed-throttle switch or TPS.
- Adjust a misaligned closed-throttle switch according to the manufacturer's procedure.
- Replace a worn closed-throttle switch.
- Correct a TPS idle-position offset or replace a faulty TPS if testing confirms it.
Can I keep driving?
If the engine idles normally and responds predictably, a short, cautious trip may be possible, but avoid heavy traffic if throttle response is erratic. Stop driving if it stalls, surges strongly, or enters reduced-power mode.
A code shows where the control module detected a fault, not always which part failed. Check the causes in order and confirm with a test before replacing parts. Have several codes? Check them together
This is a generic code: it means the same on every make. The car’s maker may add more detail in its own service information.