P0306 on Acura: How to Diagnose & Fix
Cylinder 6 Misfire Detected
2 Acura models · 2 documented issues · 1 critical · $100-$4,500 repair
P0306 on Acura by model: symptoms, diagnosis and fix
Like every C-series V6 Honda used in the 1990s and 2000s (Legend, NSX, CL, TL, RL all share the family), the RL's 3.5L C35A V6 has a distributor mounted at the back of the head and driven directly off the camshaft. Inside the distributor housing, an oil seal isolates the cam-driven shaft from the cap/rotor/electrical assembly above. By 100,000 miles the seal hardens, oil pressure forces engine oil past the shaft, and the cap fills with oil. Result: misfires (typically P0300 random plus individual cylinder codes P0301-P0306 since this is a V6), rough idle, hesitation. RepairPal explicitly lists distributor O-rings as one of the most common Acura RL oil leak points. The figure-8 oil cooler seal and oil filter housing gasket are the other two common leaks on this engine — diagnose carefully before assuming distributor. The C35A engine remained in the first-gen RL through the entire 1996-2004 production run, so this issue affects all years.
Common Symptoms
- Oil pooling inside the distributor cap when removed
- Engine misfires, especially under load or after warm-up
- Check engine light with P0300 random misfire or P0301-P0306 single-cylinder
- Rough idle that smooths out with throttle
- Visible oil at the rear of the engine, dripping down the back of the block
How to Fix
There is no replaceable seal inside the distributor — the seal is between the rotating shaft and the bearing inside the cast housing. The only fix is replacing the whole distributor assembly. OEM Honda runs $400-700; Cardone remanufactured runs $150-250. While the distributor is out, also replace the distributor cap, rotor, and ignition wires — they're cheap and you're already at the parts. Inspect the cap and rotor on the old unit for oil contamination to confirm distributor was the source. If you also see leaks elsewhere (figure-8 cooler seal, oil filter housing), address those at the same time — they share access path. Total job: 2-3 hours independent shop.
Owner tips & cautions
- TipReplace cap + rotor + ignition wires at the same time as the distributor. You're already there. Saves a future labor cycle.
- WarningDon't assume distributor without inspection. RepairPal also lists the oil cooler 'figure-8' O-ring and oil filter housing gasket as common RL leaks. Pull the cap and check for oil before buying the distributor.
Sources for this issue (2)
The 3.7L J37 V6 used in many TL SH-AWD models has a documented pattern of excessive oil consumption, sometimes leading to low oil level warnings, misfires, and spark plug fouling. Acura/Honda issued warranty extensions and service information for affected V6 engines in this family due to piston ring-related oil consumption. Owners often notice the engine using significant oil between changes, and if ignored, the condition can progress to rough running and catalyst damage risk.
Common Symptoms
- Oil level drops between oil changes
- Low oil warning or dipstick reading low
- Misfire under load or at idle
- Fouled spark plugs
- Blue smoke on startup in some cases
How to Fix
Monitor oil level closely and document consumption over a measured interval. Diagnosis typically includes checking for external leaks, inspecting plugs for oil fouling, and performing the manufacturer oil consumption test procedure. Repairs may involve updated pistons/rings under prior warranty programs or ongoing oil top-offs if consumption is mild and the vehicle is outside assistance coverage.
Owner tips & cautions
- TipCheck oil every 1,000 miles on the 3.7L, especially if service history is unknown; many owners avoid engine damage by topping off early.
Sources for this issue (2)
P0306 code reference
General diagnostic-code context. The code alone does not confirm a cause for your vehicle; use the applicable issue card and its sources.
Frequently asked questions
What does P0306 mean on a Acura?
P0306 stands for "Cylinder 6 Misfire Detected." This code means the engine computer detected a misfire on cylinder 6 — that cylinder isn't burning its fuel-air mixture properly. The computer senses misfires by watching for tiny variations in crankshaft speed each time a cylinder should fire, and when cylinder 6 repeatedly fails to contribute, this code sets. You may feel a shake or stumble, especially at idle or under load, along with reduced power and possibly a flashing check-engine light, which signals a misfire severe enough to damage the catalytic converter. A misfire comes down to a problem with spark, fuel, or compression in that cylinder. On Acura it is documented across 2 models: RL, TL.
What are the most common causes of P0306?
The most common causes of P0306 are: Worn or fouled spark plug on cylinder 6, Failed ignition coil for cylinder 6, Clogged, leaking, or failed fuel injector, Vacuum or intake air leak affecting that cylinder, Low compression (worn rings, burnt valve, head gasket), Damaged plug wire or coil connector, Carbon buildup or worn valvetrain components. The specific cause varies by vehicle.
How much does it cost to fix P0306 on a Acura?
Published repair estimates on Acura range from $100 to $4,500 depending on the model and root cause. If an issue mentions a recall or campaign, check your VIN with the manufacturer or NHTSA and confirm eligibility and coverage with a dealer.
Looking for P0306 on a different make?
View P0306 across all makes →Content compiled with AI assistance using NHTSA complaints, TSBs, and owner reports. May contain errors. Always verify with your vehicle's service manual.