P0326: Knock/Combustion Vibration Sensor A Circuit Range/Performance
What Does P0326 Mean?
P0326 is a diagnostic trouble code indicating: Knock/Combustion Vibration Sensor A Circuit Range/Performance. This code relates to the ignition system system. It has been reported in NHTSA complaints across 7 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 P0326
- ⚠️ 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
P0326 Reports by Year
Real Owner Reports
From NHTSA complaint database — actual owner descriptions.
"PURCHASED CAR FROM TOYOTA OF ROCKWALL IN JAN 2015. IN JULY 2015 STARTED HAVING ISSUES WITH SHIFT NOT COMING OUT OF PARK, SOMETIMES THE PROBLEM WOULD NOT DUPLICATE, SO I HAD TO TAKE IT BACK TO THE SHOP MULTIPLE TIMES. INITIALLY TOOK CAR TO STONEBRIAR CHEVY (FRISCO, TX), WHO REPLACED THE BATTERY. THE "
— Chevrolet Equinox owner, 11/03/2015
"UNKNOWN FULLY Engine knocking out of the blue and then died. Car went limp while driving down the road. Starts and is loudly knocking. Throws codes P0011 and P0326 Cannot drive vehicle. I have not notified hyundai yet. There were no warning lights. Car ran perfectly fine. No issues. Then the en"
— Hyundai Tucson owner, 10/27/2023
"Took my 2017 Hyundai Tucson 1.6t engine into the service center on 8/21 for a check engine light and Bluelink notification of "A possible condition with your Engine Control System has been detected" that came on Sunday 8/18. Service center diagnosed P0326 ($159.00) From the service center: We have p"
— Hyundai Tucson owner, 08/18/2024
Source: NHTSA Complaints Database
Most Reported Vehicles for P0326
Based on NHTSA owner complaint data.
| # | Vehicle | Reports |
|---|---|---|
| 1 | HYUNDAI TUCSON | |
| 2 | HYUNDAI ACCENT | |
| 3 | KIA SOUL | |
| 4 | CHEVROLET EQUINOX | |
| 5 | KIA OPTIMA | |
| 6 | KIA RIO | |
| 7 | GMC TERRAIN |
P0326 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.