OBD-II Trouble Codes

P0302 – Cylinder 2 Misfire Detected

P0302 reference anchored to the conditional RX 450h cold-start procedure in Lexus bulletin L-SB-0045-12 Rev1.

Overview

P0302 identifies a cylinder 2 misfire detection. This source-scoped entry uses Lexus L-SB-0045-12 Rev1 to demonstrate how a DTC must be combined with vehicle, operating-condition and test evidence rather than treated as a component verdict.

Within the bulletin’s RX 450h scope, P0302 is one of P0300–P0306 that can enter the workflow. The source first calls for the applicable repair-manual misfire diagnosis. Injector inspection follows only if no concern is found in the mechanical engine, engine control, ignition or fuel-supply system; replacement follows only when injector-tip debris is observed.

Code identification

Normalized Code
P0302
Code Family
P03xx Misfire
Sae Or Manufacturer Specific
Sae Generic
System Scope
Powertrain / Engine Misfire Monitoring
Short Definition
Cylinder 2 Misfire Detected.

Symptoms and risk

Plain Language Explanation

The control system detected combustion behavior consistent with a misfire at cylinder 2. The code identifies the detected cylinder, not the failed part.

Severity
Moderate
Driveability Guidance
Assess actual engine behavior and other warnings. A flashing MIL or severe rough running warrants prompt qualified diagnosis; do not continue merely because the vehicle still moves.
Common Symptoms
MIL on
rough running
cold-start roughness within this bulletin scope
Common Causes
Cause depends on vehicle and test evidence. In this bulletin’s narrow path, injector-tip debris is considered only after standard diagnosis finds no mechanical, control, ignition or fuel-supply concern.

Diagnostic path

Diagnostic Prerequisites
Confirm exact vehicle/model-year applicability, cold-soak behavior, stored DTCs, and access to current model-year service information and a compatible scan tool.
Diagnostic Steps

Follow the applicable repair-manual misfire diagnosis. Do not skip mechanical, engine-control, ignition or fuel-supply checks. Continue to the bulletin injector inspection only when those checks reveal no concern.

Common Mistakes
Replacing an injector from P0302 alone
assuming this Lexus bulletin applies to other vehicles
skipping model-year repair information
ignoring a non-matching inspection result
Clear Code Guidance
Clear stored DTCs only after completing the applicable repair and then confirm the result, as the source procedure specifies.

Technical review & evidence

Technically reviewed

Reviewer: Autool

Reviewed: 2026-08-24 13:39:42 UTC

Source updated: 20171213

References

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