P2535
Ignition Switch On/Start Position Circuit High
Ignition / starting
Generic OBD-II
Medium
What it means
P2535 means the ECM sees an abnormally high voltage on the ignition switch On/Start position circuit — the signal that tells the computer the key is in the run or start position. Because this circuit is part of the starting and power-up chain, a fault can cause hard starting, an intermittent no-start, or stalling. The cause is usually the switch, its wiring, a connector, or a related relay.
Medium
Can I keep driving? Maybe — the car often runs, but an ignition-switch circuit fault can cause hard starting, no-start, or stalling, so address it soon.
Common symptoms
What you'll notice
- Check-engine light on
- Hard starting or an intermittent no-crank / no-start
- Occasional stalling
- Accessories or warning lights behaving oddly with the key position
Common causes
Most likely first
- Short-to-voltage in the ignition On/Start signal wiringLikely
- Faulty or worn ignition switchCommon
- Faulty ignition or ECM power relayCommon
- Corroded or loose connector at the switchLess often
- Faulty ECM (least common)Less often
How to diagnose & fix
Work through it in order
- Scan and read freeze-frame data to capture when it sets.
- Inspect and wiggle-test the ignition switch connector and wiring.
- Measure the On/Start signal voltage in each key position (off, run, start).
- Check the related fuses and power relays.
- Replace the ignition switch if it tests faulty; consider the ECM last.
FAQ
Quick answers
Is it safe to drive with P2535?+
It can be, but be cautious. An ignition-switch circuit fault can lead to hard starting, a no-start, or an unexpected stall. Diagnose it before you depend on the car in an inconvenient spot.
Can I just clear P2535?+
Clearing it does not fix the switch or wiring, and it will return — possibly with a starting problem. Repair the circuit first.
Related codes
Often seen with P2535
Read & clear P2535 yourself
Scan your car, confirm the code, and clear it once it's fixed — with OBD DashX on your phone.
✓ Verified name — SAE J2012 / ISO 15031-6Guidance reviewed by OBD DashX