misfire
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Diagnostic Workspace2019 Honda Civic EX • Bay 3 • Honda Sensing
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Connected
System Health Map
● OK● Warn● Fault● ADAS
EngineTransFront BrakesRear BrakesExhaustElectricalCoolingFuel SystemIgnition Coil #1
Engine RPMrpm
1,850
Coolant Temp°C
92
Vehicle Speedkm/h
65
Throttle%
18
STFT Bank 1%
8.6
BatteryV
14.2
Diagnostic Trouble Codes
1 Critical2 Warning
P0301critical
Cylinder 1 Misfire Detected
Engine / Ignition
P0171warning
System Too Lean (Bank 1)
Fuel & Air Metering
P0420warning
Catalyst Efficiency Below Threshold
Emissions
Freeze Frame — P0301
Engine Load
68.2%
RPM
3,200
Speed
72 km/h
STFT B1
+8.6%
LTFT B1
+4.2%
Coolant
88°C
Intake Air
31°C
MAF Rate
18.45 g/s
Throttle
48.2%
Fuse Box Layout
Engine compartment, driver side
F1
40A
F2
30A
F3
20A
F4
20A
F5
15A
F6
15A
F7
15A
F8
10A
F9
15A
F10
20A
F11
30A
F12
10A
P0301Claude Opus
Cylinder 1 Misfire Detected
Primary Diagnosis
Cylinder 1 Misfire — Likely Ignition Coil Failure
87%
High confidence — Proceed with repair
Evidence & Reasoning
DTC correlation35%
P0301 + P0171 (lean) suggest ignition-related lean condition, not fuel delivery
Freeze frame30%
Captured at 3200 RPM, 68% load — misfire under load points to weak spark, not vacuum leak
Fuel trim analysis25%
STFT +8.6% Bank 1 — lean condition consistent with cylinder not firing (unburnt O2)
Historical pattern10%
2018-2020 Civic 2.0L: ignition coil failure common at 60K+ miles
Verification Steps
1
Measure coil #1 primary resistance (spec: 0.5-0.7Ω)
2
Compare spark duration coil #1 vs #2-4 with oscilloscope
3
Check connector for corrosion or loose fit
Recommended Parts
Ignition Coil (Denso 673-2318)
$32-45In stock at AutoZone, O'Reilly
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Repair Context
○ADAS Awareness
Honda Sensing6 systems
Camera-only (no front radar on Civic)
AEBACCLKALDWRDMAHBBSM
i
Honda Sensing
Ignition coil replacement does NOT affect ADAS sensors.
No ADAS action needed.