P0394: Camshaft Position Sensor B Circuit Intermittent Bank 2
What Does P0394 Mean?
P0394 is a diagnostic trouble code indicating: Camshaft Position Sensor B Circuit Intermittent Bank 2. This code relates to the ignition system system. It has been reported in NHTSA complaints across 1 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 P0394
- ⚠️ 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
P0394 Reports by Year
Real Owner Reports
From NHTSA complaint database — actual owner descriptions.
"BEGINNING OF FEB., LOST POWER ON FREEWAY. WENT FROM 65 TO 40 MPH AND COULD NOT ACCELERATE. ENGINE AND TRACTION LIGHTS CAME ON. EXITED THE FWY AND DROVE TO DEALER WHERE I WAS TURNED AWAY DUE TO HIGH VOLUME. LEFT MY JEEP AT THE DEALER THE FOLLOWING DAY WITH THIS ISSUE AND TO CORRECT CAMPAIGN #V51 "
— Jeep Wrangler owner, 03/18/2020
"Check engine light on, OBD codes P0016, P0390, P0394. Replaced camshaft and crankshaft sensors and problem still persists; limp mode up hills, and oil loss. Per MULTIPLE Jeep Wrangler forums, this is a very wide-spread Jeep phenomenon. Dealers do not know how to fix this. Jeep needs to own up to thi"
— Jeep Wrangler owner, 07/12/2021
Source: NHTSA Complaints Database
Most Reported Vehicles for P0394
Based on NHTSA owner complaint data.
| # | Vehicle | Reports |
|---|---|---|
| 1 | JEEP WRANGLER |
P0394 Reports by Vehicle
Detailed NHTSA complaint analysis for each vehicle model.
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?
Can misfires damage my engine?
Why does my car misfire only when cold?
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)
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Find your vehicle above
Click your make and model for real owner reports and common causes specific to your vehicle.
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Check for recalls
Go to nhtsa.gov/recalls and enter your VIN. Free repairs if covered.
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Get a professional diagnosis
A code alone doesn't identify the exact failed part. A diagnostic ($50–$150) pinpoints the root cause.