DIYAUTOFIXESMANUALS

Diagnostic Trouble Code Database

P0302Severe (Stop & Fix)

Cylinder 2 Misfire Detected

System:Ignition & Combustion•Classification:Powertrain (OBD-II Generic)•Severity Impact:Active cylinder misfire dumps unburned fuel directly into catalytic converter. Flashing CEL risks melting internal ceramic honeycomb substrate.
Direct Technical Definition (Fast Answer)

Code P0302 indicates that the engine control module (ECM) detected a loss of crankshaft rotational speed specifically when cylinder 2 fired. In over 75% of cases, this is caused by a failing cylinder 2 ignition coil boot, fouled spark plug, or leaking fuel injector.

Estimated Repair Time20 – 45 minutes
DIY Parts Cost$15 – $65
Shop Repair Quote$180 – $380
Average DIY Savings$165 – $315
The 80/20 Workshop Rule

Perform the coil swap test: Move the cylinder 2 ignition coil to cylinder 1, clear the codes, and test drive. If the fault moves to P0301, replace the defective ignition coil ($35). If misfire stays on P0302, replace the spark plug.

Estimated DIY Cost
$15 – $65
Tools & DIY parts
Dealership Shop Quote
$180 – $380
Labor ($180/hr) + parts
Net Money Saved
$165 – $315
In your driveway today

Interactive Symptom Pinpoint Troubleshooter

Answer 2 diagnostic tests to isolate the exact component failure for P0302.

DIAGNOSTIC TEST 1 OF 1Step 1

When you swap the ignition coil from Cylinder 2 to Cylinder 1, does the diagnostic trouble code change from P0302 to P0301?

Live Scanner & Multimeter Benchmark Values

Compare your live OBD-II PID sensor data against OEM factory operating specs for P0302.

Monitored Parameter / Sensor PIDHealthy OEM Operating RangeFault Threshold (Triggers P0302)
Cylinder 2 Ignition Coil Primary Resistance
0.5 – 1.8 Ohms
OL (Open Loop) or 0.0 Ohms indicates shorted internal winding
Spark Plug Gap (Spec)
0.038" – 0.044" (refer to hood sticker)
>0.065" gap strains ignition coil secondary voltage
Cylinder 2 Fuel Injector Resistance
11.5 – 14.5 Ohms at 68°F
<8.0 Ohms (shorted) or >18 Ohms (high resistance coil)

Symptoms Associated with P0302

Drivers typically observe the following symptoms when the ECM flags P0302:

Check Engine Light on (flashing under acceleration)
Noticeable engine shudder or vibration at idle
Hesitation and sluggish throttle response when climbing hills
Strong smell of unburned raw gasoline from tailpipe
Increased fuel consumption

Common Root Causes & Statistical Probability Matrix

Statistical breakdown of what triggers this code based on automotive repair shop data.

Failing cylinder 2 ignition coil pack or torn rubber boot
High ProbabilityDifficulty: Easy
Relative Frequency: 75%Estimated Parts Cost: Low
Worn, fouled, or improperly gapped spark plug
High ProbabilityDifficulty: Easy
Relative Frequency: 75%Estimated Parts Cost: Low
Clogged or leaking cylinder 2 fuel injector
Medium ProbabilityDifficulty: Moderate
Relative Frequency: 45%Estimated Parts Cost: Medium
Low mechanical compression (tight valve, blown head gasket)
Low ProbabilityDifficulty: Hard
Relative Frequency: 20%Estimated Parts Cost: High

Step-by-Step Diagnostic & Repair Procedure

Follow this logical order to isolate and repair P0302 before spending money on costly parts.

Checklist Progress: 0 of 3 steps complete

Step 1: Coil Swap Verification

Unplug and swap cylinder 2 coil with adjacent cylinder 1. Clear codes. If code shifts to P0301, coil is bad.

Step 2: Spark Plug Inspection

Remove cylinder 2 spark plug. Check for carbon soot, oil on porcelain, or burnt electrodes.

Step 3: Fuel Injector Click & Resistance Test

Listen with mechanic stethoscope for rapid clicking at idle. Measure injector resistance (spec: 12-15Ω).

Vehicle-Specific Failure Trends & Technical Bulletins

Real workshop failure patterns reported by mechanics across popular makes and models for P0302.

Ford F-150 / Expedition (5.4L / 3.5L EcoBoost)

Common Failure Point:Moisture or oil pools inside deep cylinder 2 spark plug well, causing high-voltage spark blowout through cracked rubber coil boot.
Verified Workshop Fix:Blow out well with compressed air, install new spark plug and coil boot with dielectric grease.

Honda Civic / Accord (1.5T / 2.4L)

Common Failure Point:Direct injection fuel injector tip carbon deposits cause cylinder 2 lean misfire under light throttle.
Verified Workshop Fix:Run Techron fuel system cleaner or replace injector assembly.

BMW 3-Series / 5-Series (N20 / N55 / B58)

Common Failure Point:Delphi ignition coil potting epoxy develops microscopic thermal cracks after 60,000 miles.
Verified Workshop Fix:Swap cylinder 2 coil with cylinder 3 to confirm, replace with updated Eldor coil ($42).

Dave Miller, ASE Master Tech

ASE L1 Certified Master Reviewer

ASE Certified Master Automobile Technician (A1-A8) & L1 Advanced Engine Performance • 24 years automotive diagnostic experience

“Always verify sensor voltages and harness grounds before purchasing replacement electronic components.”

Editorial review and field diagnostic verification: Updated October 2026

Frequently Asked Questions About P0302

Only if the Check Engine Light is solid and you are driving gently to your garage. If the light is flashing, pull over immediately; raw gasoline will ignite inside the catalytic converter and destroy it in minutes.