- Vehicles
- Cars
P0301
Toyota P0301: cylinder 1 misfire detected
Evidence linked to this decision
View source: Toyota T-SB-0148-19 Highlander HV P0301-P0306Risk level
High
Professional inspection is recommended.
Urgency
High
Quick answer
Toyota detected misfire on cylinder 1; that does not prove its ignition coil is faulty. Lamp behavior, companion misfire codes and exact hybrid scope come before coil or ECM work.
Safety first
Stop and check this first
- Do not reproduce a fault on the road. Stop driving for a flashing engine light, severe power loss, smoke, fuel smell, overheating, abnormal mechanical noise, no-start or reduced steering assist.
Safe checks you can perform
- Preserve the evidence before any reset
- Use the observation that changes the path
- Test the official bulletin boundary
Leave these tasks to a qualified professional
- Do not attempt this professional task: Request a measurement-led diagnosis
- Do not attempt this professional task: diagnosed cylinder-1 coil fault
What a technician must be able to justify
Technician visit
These are the steps they must carry out and show you. Tick them as they work: if steps are skipped, do not accept a part swap.
These are not instructions for opening or handling the equipment yourself. They are the checks that should support a technical conclusion.
Request a measurement-led diagnosis
What they doRun the Toyota P0300-P0306 repair-manual diagnosis, document the cylinder test and compare ECM calibration only if the coil fault is proven.
diagnosed cylinder-1 coil fault
What they doAsk which test proved cylinder 1, whether the fault followed a component and whether calibration IDs match.
Before accepting a part or repair
Nothing has been shown yet. Do not accept a part swap based on the code alone.
Follow these steps
Note: Follow the documented order. An error code identifies the affected system, but it does not prove by itself which part has failed.
Preserve the evidence before any reset
Save P0301, every accompanying DTC, freeze-frame values, readiness state and the module that reported it. Record the VIN, model year, engine, market and symptoms. Do not clear codes or disconnect the battery yet.
Do not reproduce a fault on the road. Stop driving for a flashing engine light, severe power loss, smoke, fuel smell, overheating, abnormal mechanical noise, no-start or reduced steering assist.
Evidence: Toyota T-SB-0148-19 Highlander HV P0301-P0306
Use the observation that changes the path
Whether the lamp flashed, engine ran rough and P0300/P0302-P0306 accompanied P0301 is recorded
Do not reproduce a fault on the road. Stop driving for a flashing engine light, severe power loss, smoke, fuel smell, overheating, abnormal mechanical noise, no-start or reduced steering assist.
Evidence: Toyota T-SB-0148-19 Highlander HV P0301-P0306
Test the official bulletin boundary
2017-2019 Toyota Highlander Hybrid, and only after the repair-manual diagnosis identifies a malfunctioning ignition coil
A matching code is not enough: every model, engine, market and build condition must match.
Evidence: Toyota T-SB-0148-19 Highlander HV P0301-P0306
Still not solved
If the error persists, stop here. See what the technician must do and show you.
Virtual technician
Does P0301 still appear after these checks?
This guided flow uses the exact code and your answers to choose a test, an expected result and the next branch.
Where this code applies
A code is meaningful only inside the right product and version context.
Primary scope
- System
- Vehicles
- Brand
- Toyota
- Product type
- Cars
Known code variants
- P0301
- P0301 code Toyota
- P0301 cylinder 1 misfire
- P0301 fallo de encendido cilindro 1
- P0301 OBD2
- P0301 Toyota
- Toyota P0301
What it means
Toyota's bulletin continues to coil replacement and ECM calibration only after model-specific diagnosis proves the coil fault. If the coil is not proven or the model is outside scope, the bulletin stops and the exact repair-manual misfire tree remains required. 2017-2019 Toyota Highlander Hybrid, and only after the repair-manual diagnosis identifies a malfunctioning ignition coil
Warnings and stop conditions
- Highsource verified
Do not reproduce a fault on the road. Stop driving for a flashing engine light, severe power loss, smoke, fuel smell, overheating, abnormal mechanical noise, no-start or reduced steering assist.
Evidence: Toyota T-SB-0148-19 Highlander HV P0301-P0306
Symptoms and causes
Probable causes · in order
- diagnosed cylinder-1 coil faultPossible
Toyota's bulletin continues to coil replacement and ECM calibration only after model-specific diagnosis proves the coil fault.
Evidence: Toyota T-SB-0148-19 Highlander HV P0301-P0306
- another ignition, fuel or mechanical misfire causePossible
If the coil is not proven or the model is outside scope, the bulletin stops and the exact repair-manual misfire tree remains required.
Evidence: Toyota T-SB-0148-19 Highlander HV P0301-P0306
Sources and technical references
- 1
Toyota T-SB-0148-19 Highlander HV P0301-P0306
Toyota Motor Sales USA · 2019 · service_bulletin
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