P0366 — Camshaft Position Sensor B Circuit Range/Performance Bank 1

What Does P0366 Mean?

P0366 is a diagnostic trouble code indicating: Camshaft Position Sensor B Circuit Range/Performance Bank 1. This code relates to the ignition system system. It has been reported in NHTSA complaints across 4 different vehicle models.

Engine misfires are detected by monitoring crankshaft rotational speed variations. Each cylinder's power stroke produces a characteristic acceleration pattern. When a cylinder fails to fire, the crankshaft decelerates during that cylinder's stroke. The ECM identifies which cylinder misfired and how often. P0313-P0399 codes cover extended misfire monitoring including lean misfire detection, knock-related ignition faults, and secondary ignition monitoring. A flashing check engine light during active misfires is an emergency — raw unburned fuel enters the catalytic converter, potentially destroying it.

Symptoms of P0366

⚠️ Check engine light on (may flash during active misfire)
⚠️ Engine misfiring — rough idle, stumbling, shaking
⚠️ Loss of power during acceleration
⚠️ Increased emissions and fuel consumption
⚠️ Catalytic converter damage if ignored
⚠️ Possible engine vibration at idle

Common Causes

🔍 Worn or fouled spark plugs
🔍 Faulty ignition coil
🔍 Vacuum leak causing lean misfire
🔍 Fuel injector issue (clogged, leaking, or electrical)
🔍 Low compression (worn rings, burned valve, head gasket)
🔍 Incorrect ignition timing

P0366 Reports by Year

2018

1

2024

1

2025

1

2019

1

Real Owner Reports

From NHTSA complaint database — actual owner descriptions.

"ON JAN 13 MY CHECK ENGINE LIGHT CAME ON I DIDN'T HAVE ANY PROBLEMS WITH THE CAR BEFORE THIS AND I WENT TO SCHOOL WHEN STARTING THE CAR AT 5PM WITH NO PROBLEMS. I WAS DRIVING HOME AND IT SMELLED REALLY BAD SO I STOPPED THE CAR AND OIL WAS LEAKING OUT EVERYWHERE. I HAD AUTO ZONE PULL THE CODES AND WHE"
— Chevrolet Equinox owner, 01/13/2018

"The contact called on behalf of a customer who owns a 2019 Hyundai Elantra. The contact stated the vehicle stalled without warning while driving at various speeds. The owner brought the vehicle to the independent mechanic where the contact, diagnosed the vehicle and retrieved DTC code: P0366 (Cam Po"
— Hyundai Elantra owner, 07/23/2024

"I'm the owner of a 2019 Hyundai Kona (US spec) imported to Poland. The VIN is included in recall 21V-301 (fire risk). The engine showed symptoms consistent with this defect and failed at 44,000 miles. Photos confirm cylinder damage. Following Hyundai Motor America (HMA) instructions, I completed di"
— Hyundai Kona owner, 06/10/2025

Source: NHTSA Complaints Database

Most Reported Vehicles for P0366

Based on NHTSA owner complaint data.

#	Vehicle	Reports
1	CHEVROLET EQUINOX
2	HYUNDAI ELANTRA
3	HYUNDAI KONA
4	GMC TERRAIN

Diagnostic Tips

Check misfire counters in Mode 6 data — identifies which cylinder(s) are misfiring most
Swap ignition coil to another cylinder — if misfire follows, coil is bad
Check spark plugs — worn electrode, fouled with oil or carbon, cracked insulator all cause misfires
Perform compression test on affected cylinder(s) — low compression means mechanical issue

Common Mistakes to Avoid

❌ Replacing coils without checking spark plugs — a worn plug will kill a new coil
❌ Ignoring a flashing check engine light — this means severe misfire that's damaging the catalytic converter NOW
❌ Replacing ignition parts when the misfire is caused by a vacuum leak or low compression

Frequently Asked Questions

What does a flashing check engine light mean?

A flashing CEL means severe, active misfire that risks catalytic converter damage. Pull over safely and reduce engine load. Do not rev the engine. Drive gently to a repair facility or have it towed. This is the only CEL condition that warrants immediate action.

Can misfires damage my engine?

Misfires themselves don't usually damage the engine, but they can destroy the catalytic converter ($1000-$3000). Severe misfires also dilute engine oil with raw fuel, reducing lubrication. Extended misfires should always be repaired promptly.

Why does my car misfire only when cold?

Cold misfires are often caused by slightly worn spark plugs (gap too wide for cold, dense air-fuel mixture), marginal ignition coils that work fine once warm, or small vacuum leaks that are more noticeable at cold idle RPM.

What To Do Next

Possible Fixes

🔧 Replace spark plugs
🔧 Replace ignition coil(s)
🔧 Repair vacuum leak
🔧 Clean or replace fuel injector
🔧 Engine mechanical repair (valves, rings, gasket)

1
Find your vehicle above
Click your make and model for real owner reports and common causes specific to your vehicle.
2
Check for recalls
Go to nhtsa.gov/recalls and enter your VIN. Free repairs if covered.
3
Get a professional diagnosis
A code alone doesn't identify the exact failed part. A diagnostic ($50–$150) pinpoints the root cause.

P0366: Camshaft Position Sensor B Circuit Range/Performance Bank 1