P0301: Cylinder 1 Misfire Detected
The ECM detects consistent deceleration of the crankshaft specifically during the power stroke of Cylinder #1. Cylinder 1 is the reference cylinder positioned closest to the front timing belt/chain.
Driveability & Safety Advisory
Drive only short distance directly to a repair shop. Driving with an active dead cylinder causes severe engine imbalance and unburned fuel contamination of engine oil.
Official Manufacturer TSB Advisories
Factory Condition: Defective ignition coil internal transistor causes intermittent spark failure on Cylinder 1 under engine load.
Physical Component Location & Service Access
Cylinder #1 is the front-most cylinder on inline-4 and inline-6 engines. On V6/V8 engines, Cylinder 1 is the leading cylinder on the bank that sits slightly further forward on the engine block.
Electrical Specifications & Live PID Benchmarks
Scan Tool Live Data Targets
Digital Multimeter (DMM) Specs
Documented Model-Specific Case Studies
Root Cause: Blown head gasket between Cylinder 1 and cooling jacket allows coolant seepage into Cylinder 1 overnight, causing misfire on morning start.
Verified Fix: Perform block leak test (combustion gas in coolant); replace head gasket with revised MLS gasket.
Technician Inspection & Testing Workflow
The 'Swap Test' (Golden Rule of Diagnostics): Swap Cylinder 1 ignition coil to Cylinder 2. Clear codes and test drive. If misfire moves to Cylinder 2 (code changes to P0302), the coil is bad. If misfire stays on Cylinder 1, swap spark plug to Cylinder 3.
If misfire remains on Cylinder 1 after swapping coil and plug, use a noid light to verify ECM injector pulse signal.
Perform a mechanical compression check on Cylinder 1. Compare reading to adjacent Cylinder 2.
Recommended Diagnostic Tools & Verified Parts
BlueDriver Bluetooth Pro OBDII Scan Tool
Wireless sensor telemetry & enhanced diagnostics (Engine, ABS, Airbag). Delivers verified vehicle repair reports.
Autel AutoLink AL519 / AL319 OBD2 Scanner
Color screen standalone scanner. One-click I/M emissions readiness status, freeze-frame data, live DTC reset.
Ram-Pro Inline Engine Ignition Spark Tester & Gap Gauge
Quickly verify if spark plug coils are firing with high-intensity visual spark indicator. Includes electrode gap measure tool.
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Cost Breakdown
Tools & Parts Matrix
Diagnostic Questions & Answers
What is the fastest way to confirm a bad ignition coil on Cylinder 1?
Swap the coil with Cylinder 2. If the scanner now reports P0302, the coil has failed.