P0302 on Acura: How to Diagnose & Fix
Cylinder 2 Misfire Detected
6 Acura models · 6 documented issues · 3 critical · $80-$4,500 repair
P0302 on Acura by model: symptoms, diagnosis and fix
The base second-generation TLX uses a 2.0L turbocharged four with a front-mounted air-to-air intercooler. In humid, rainy or cold-and-damp conditions, water vapor condenses inside the intercooler and charge piping, pools, and is then slugged into the intake on a throttle transition. The result is a sudden multi-cylinder misfire, a stumble or hard bucking under acceleration, and in many cases a drop into limp mode with reduced power until the ignition is cycled. NHTSA complaints on the 2021 TLX describe 'turbo intercooler water vapor accumulation causing misfires and limp-mode activation during humid/rainy conditions' and sudden power loss during acceleration. This is specific to the turbocharged four - the Type S 3.0T uses a different charge-air layout, and the first-generation naturally aspirated engines have no intercooler at all.
Common Symptoms
- Sudden misfire and bucking under acceleration in rain, fog or high humidity
- Check engine light with random/multiple cylinder misfire codes
- Limp mode with reduced power until the ignition is cycled
- Symptoms absent in dry weather
- Water audible sloshing in the charge piping
- Puff of white vapor from the exhaust on the misfire event
How to Fix
Have misfire codes read - random/multiple-cylinder misfire codes appearing only in wet or humid weather, with no fuel-trim or ignition fault, point to condensation rather than coils or plugs. Do not let a shop replace coils and plugs as a first move on a weather-correlated misfire. The dealer path is an ECU/PCM software update where one is available for your VIN plus inspection of the intercooler and charge piping for pooled water and for a low spot or sagging hose that traps it; correcting charge-pipe routing and clearing any blocked intercooler drain resolves most cases. Recurrent cases are addressed with an intercooler assembly replacement under the 4yr/50k warranty. Avoid aftermarket 'fixes' that drill the intercooler - they create a boost leak.
Sources for this issue (2)
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 ignition distributor on 1990-2001 Integras (and all Honda B-series engines of the era) sits at the rear of the head and is driven directly off the exhaust cam. Inside the distributor housing, an oil seal separates the cam-driven shaft from the cap/rotor/electrical assembly above it. When this seal hardens with age and heat cycling, engine oil under pressure leaks past the shaft, fills the cap area, and coats the rotor and contacts. Result: misfires, hard starts, hesitation, stalling at idle, and sometimes a check-engine light for misfire codes. The shaft seal CAN technically be replaced internally, but it is difficult and many shops will not attempt it — they replace the whole distributor instead because reused housings often re-leak quickly. Cleaning the cap helps for a few weeks and then symptoms return.
Common Symptoms
- Oil pooling visibly inside the distributor cap when removed
- Engine misfires intermittently, especially under load or after warm-up
- Stalling at idle once the engine is hot
- Hard start when warm (oil-fouled rotor won't conduct)
- Check engine light with P0301-P0304 misfire codes
- Briefly improves after distributor cleaning, returns within weeks
How to Fix
Replace the complete distributor. OEM Honda distributors are pricey ($350-500+) but reliable; aftermarket units from Cardone, A1 Cardone, or Spectra Premium are $80-150 and work fine for non-track use. While the distributor is out, also replace the cap, rotor, and ignition wires — they're cheap and replacing them at the same time saves a labor cycle. After install, time the engine to factory spec (16°±2° BTDC at idle with timing-adjust connector unplugged). Do NOT just clean the cap and call it done — the oil keeps coming and you'll be back in 6 weeks. If you're keeping the car long-term, the Honda OEM distributor outlasts aftermarket 2:1.
Owner tips & cautions
- TipReplace the cap, rotor, and ignition wires at the same time as the distributor. They're cheap and you're already in there — saves a future labor cycle.
- WarningDo NOT just clean the cap and call it fixed. The internal oil leak keeps coming. Cleaning buys you 4-6 weeks before symptoms return.
Sources for this issue (2)
K-series engines use solid rocker-and-screw valve adjusters with no hydraulic lash compensation, so clearance must be checked and reset by hand. The RSX factory service manual only calls for it at 110,000 miles, and the community's repeated finding is that this interval is far too long: owners routinely find valves well out of specification at 30,000-60,000 miles. Because the valves recede into the seats as they wear, clearance TIGHTENS rather than opens - and a valve held slightly off its seat cannot shed heat, which is how K-series engines have gone on to burn and drop exhaust valves. Early symptoms are a subtle loss of power and crispness rather than noise, which is exactly why the check gets skipped. Both the base K20A3 and the Type-S K20A2/K20Z1 are affected, though the higher-revving, higher-compression Type-S engines see it sooner.
Common Symptoms
- Gradual loss of power and throttle crispness
- Rough idle or occasional misfire
- Ticking from the valvetrain (or, more dangerously, no noise at all as clearance tightens)
- Low compression on one cylinder
- Hard starting when hot
How to Fix
Check and adjust valve clearance every 30,000-40,000 miles rather than waiting for 110,000 - this is the single highest-value preventive service on a K20. Specification on the K20A2 is 0.21-0.25 mm (.008-.010 in) intake and 0.28-0.32 mm (.011-.013 in) exhaust; measure with the engine fully cold and the cam lobes pointing away. Adjustment is done by loosening the outer 10 mm locknut and setting the gap with the center screw. Owners consistently report a noticeable return of power and throttle response afterward. If exhaust clearance is already at or near zero, do a compression or leakdown test before assuming an adjustment fixes it - a receded, heat-damaged valve needs a head off and seat work.
Sources for this issue (4)
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)
P0302 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 P0302 mean on a Acura?
P0302 stands for "Cylinder 2 Misfire Detected." This code means the engine computer has detected a misfire specifically in cylinder 2, meaning that cylinder isn't completing combustion properly on some firing events. The computer watches tiny variations in crankshaft speed to spot when a cylinder fails to fire, and a misfire means the air-fuel mixture isn't igniting correctly — usually from a spark, fuel, or compression problem in that cylinder. You may feel a stumble, rough idle, shaking, loss of power, or a flashing check-engine light, and persistent misfires can damage the catalytic converter. Because it names a single cylinder, the fault is often a component serving just cylinder 2, like its coil, plug, or injector. On Acura it is documented across 6 models: TLX, RL, MDX, Integra, RSX, TL.
What are the most common causes of P0302?
The most common causes of P0302 are: Worn or fouled spark plug (cylinder 2), Failed ignition coil or coil-on-plug (cylinder 2), Clogged or faulty fuel injector (cylinder 2), Vacuum or intake air leak affecting that cylinder, Low compression (worn rings, burnt/bent valve, head gasket), Damaged spark plug wire or boot (if equipped), Carbon-tracked or cracked coil/plug causing spark loss, Faulty PCM/ECM driver (rare). The specific cause varies by vehicle.
How much does it cost to fix P0302 on a Acura?
Published repair estimates on Acura range from $80 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 P0302 on a different make?
View P0302 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.