P0321 Code: Engine Speed Input Signal Out of Range
🟠 Moderate severity · drivable
Drivable, but the engine may run rough, misfire, or stall, so get it checked soon.
What P0321 means
The engine computer is receiving a signal that tells it how fast the engine is spinning, but the signal values are out of the expected range. On most cars this speed signal comes from the crankshaft position sensor, and on older cars from the distributor. Without a clean speed reading, the computer can't time the spark and fuel correctly.
Symptoms
- Check engine light is on
- Rough running or misfire
- Hard starting
- Engine stalling
Common causes
- most common: Faulty crankshaft position sensor
- common: Damaged wiring or loose connector at the sensor
- less common: Worn distributor pickup on older cars
- rare: Damaged reluctor ring or flywheel
How to fix it
| Fix | DIY? | Typical cost |
|---|---|---|
| Inspect and clean the sensor connector and wiring | Yes | $0–10 |
| Replace the crankshaft position sensor | Yes | $50–200 |
| Have a shop test the engine speed signal with a scan tool | Mechanic | $80–150 |
Frequently asked questions
Can I drive with a P0321 code?
Yes, but the engine may run rough or stall. Get it checked soon.
What is the most common cause of P0321?
A faulty crankshaft position sensor or damaged wiring to it.
How much does it cost to fix a P0321?
Typically $50–$200 for a new crankshaft position sensor.
Related codes
P0322
P0322 Code: Engine Speed Input Signal Missing
P0323P0323 Code: Engine Speed Input Signal Intermittent
P0335P0335 Code: Crankshaft Position Sensor Circuit Malfunction
Updated 2026-08. This page is informational and not a substitute for professional diagnosis.