P0301 on a 2012 Toyota Tacoma
Cylinder 1 Misfire
P0301 on a 2012 Toyota Tacoma indicates cylinder 1 misfire. Stop driving and diagnose it before continuing — it can signal an unsafe condition. The most common cause is failed ignition coil on cylinder 1 (typically $80–$450). Confirm the root cause before replacing parts.
What does P0301 mean on a 2012 Toyota Tacoma?
P0301 is set when the engine control module's misfire monitor detects that combustion is failing specifically in cylinder 1. The ECM identifies the affected cylinder by correlating crankshaft deceleration with camshaft position. The fact that only cylinder 1 is misfiring narrows the cause to parts that are specific to that cylinder — its plug, coil, injector, compression, or in some cases its harness wiring.
This guide covers P0301 across the 2010-2014 Toyota Tacoma generation — the symptoms, causes, and diagnostic steps below apply to every model year from 2010 through 2014.
Is it safe to drive a 2012 Toyota Tacoma with P0301?
No. P0301 is a high-severity code on the 2012 Toyota Tacoma — avoid driving until it is diagnosed and repaired, as it can indicate an unsafe condition or risk further damage.
What are the symptoms of P0301 on a 2012 Toyota Tacoma?
- Check Engine Light steady or flashing depending on misfire severity
- Distinct rough idle that smooths out at higher RPM
- Stumble or hesitation under acceleration
- Reduced engine power
- Smell of unburned fuel from the exhaust
- Faint exhaust pop or backfire on overrun in severe cases
What causes P0301 on a 2012 Toyota Tacoma?
| Cause | Likelihood | Estimated repair (USD) |
|---|---|---|
| Failed ignition coil on cylinder 1 On coil-on-plug engines this is the single most likely cause. | Most common | $80–$450 |
| Worn, fouled, or wrong-gap spark plug in cylinder 1 | Most common | $15–$80 |
| Clogged, leaking, or electrically failed injector on cylinder 1 | Common | $150–$800 |
| Burnt exhaust valve or low compression on cylinder 1 | Occasional | $800–$3,500 |
| Damaged or chafed wiring to the cylinder 1 coil or injector | Occasional | $80–$300 |
| Cracked cylinder 1 intake runner or local vacuum leak | Rare | $100–$600 |
How to diagnose this on a 2012 Toyota Tacoma
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Confirm cylinder 1 location on this engine
Cylinder 1 numbering differs by manufacturer. On most inline engines cylinder 1 is at the front. On most transverse V6s cylinder 1 is on the bank closer to the firewall. Consult the service manual before pulling parts.
Tools: Vehicle-specific service information
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Swap the cylinder 1 ignition coil with a known-good cylinder
Move the cylinder 1 coil to cylinder 2 (or any non-misfiring cylinder), and move that coil to cylinder 1. Clear codes and drive. If the misfire follows the coil to its new cylinder, replace the coil. If the misfire stays in cylinder 1, the coil is fine.
Tools: Socket set
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Swap the cylinder 1 spark plug
Use the same swap method with the spark plug. Inspect the removed plug first — a wet, fuel-soaked plug means no spark or no compression; a black sooty plug means a rich condition; a cracked ceramic means replace immediately.
Tools: Spark plug socket, Extension and ratchet
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Test the cylinder 1 injector electrically and acoustically
Listen to the injector with a stethoscope at idle — it should click rhythmically. A "noid light" or scan tool fuel-injector test confirms that the ECM is firing the injector. If it pulses but the cylinder still misfires, the injector may be clogged or leaking.
Tools: Mechanic's stethoscope, Noid light kit or scan tool injector test
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Perform a wet/dry compression test on cylinder 1
Measure compression on cylinder 1 cold and warm. If significantly lower than the other cylinders, add a teaspoon of oil through the plug hole and retest. Pressure that rises with oil points to worn rings; pressure that stays low points to valves or the head gasket.
Tools: Compression tester, Engine oil
NHTSA complaints & recalls for the 2012 Toyota Tacoma
Owner-reported safety complaints and official recalls filed with the U.S. National Highway Traffic Safety Administration for the 2012 Toyota Tacoma. Use these to gauge how common a problem is on your specific vehicle before you start chasing Toyota Tacoma diagnostics.
- ENGINE 122
- POWER TRAIN 35
- VEHICLE SPEED CONTROL 22
- FUEL/PROPULSION SYSTEM 51
- UNKNOWN OR OTHER 43
7 active recalls
- STRUCTURE:BODY:HOOD:HINGE AND ATTACHMENTS Jul 2017
Southeast Toyota Distributors, LLC (SET) is recalling certain 2011-2016 Toyota Tacoma and 4Runner vehicles equipped with accessory hood scoops installed by SET or SET dealers. The adhesive attaching the hood scoop may weaken, allowing the hood scoop to detach from the vehicle.…
NHTSA campaign 17V425000 - SERVICE BRAKES, HYDRAULIC:ANTILOCK/TRACTION CONTROL/ELECTRONIC LIMITED SLIP:CONTROL UNIT/MODULE Feb 2014
Toyota is recalling certain model year 2012 and 2013 Toyota Tacoma and Lexus RX350 vehicles and certain model year 2012 Toyota Rav4 vehicles. In the affected vehicles, the brake system contains a brake actuator that adjusts the fluid pressure of each wheel cylinder. An electric…
NHTSA campaign 14V054000 - EQUIPMENT:OTHER:LABELS Aug 2014
Toyota Motor Engineering & Manufacturing (Toyota) is recalling certain model year 2008-2014 FJ Cruiser and Tacoma vehicles equipped with accessory wheels and tires installed by Toyota or dealers prior to the vehicle's first sale. The affected vehicles may list incorrect spare ti…
NHTSA campaign 14V475000 - TIRES:TEMPORARY/EMERGENCY SPARE TIRE Oct 2013
Southeast Toyota Distributors, LLC (SET) is recalling certain model year 2012-2013 Tacoma vehicles equipped with 18" Maverick Alloy Wheels. In the affected vehicles, the spare tire requires the use of a different style of lug nut to attach it to the vehicle than the other wheels…
NHTSA campaign 13V494000
How do I fix P0301 on a 2012 Toyota Tacoma?
- Replace the cylinder 1 ignition coil
- Replace all spark plugs (always replace as a complete set)
- Replace, clean, or service the cylinder 1 fuel injector
- Repair damaged harness wiring to cylinder 1
- Head work or engine rebuild for compression-related root causes
About the 2010-2014 Toyota Tacoma
The 2010-2014 Toyota Tacoma was commonly sold with the following powertrains: 2.7L I4, 3.5L V6, 4.0L V6. Common trims include SR, SR5, TRD Sport, TRD Off-Road, Limited.
Why isolated-cylinder misfires are easier than P0300 alone
When the ECM can attribute the misfire to one specific cylinder, the diagnostic path is short: there are only a handful of parts unique to that cylinder. The swap test (move the coil to a different cylinder, see if the misfire follows) typically resolves a P0301 within 15 minutes of hands-on work.
When P0301 follows a coil but the coil tests good
Aftermarket coils — especially the discount bulk packs sold online — can test fine on the bench but fail under cylinder-pressure load. If a brand-new coil sets P0301 within days, replace it with an OEM or premium-aftermarket part. This is especially common on Ford modular engines and GM L83/L86 truck V8s.
P0301 on a direct-injection engine
On direct-injection engines (most modern Hondas, Mazdas, Hyundais, and many Fords from 2012 onward), carbon buildup on intake valves can cause single-cylinder misfires that ignition and fuel work will not fix. A borescope inspection through the intake port reveals the carbon. Walnut-shell blasting restores normal operation.
P0301 on a 2012 Toyota Tacoma: frequently asked questions
What does diagnostic trouble code P0301 mean on a 2012 Toyota Tacoma?
P0301 is set when the engine control module's misfire monitor detects that combustion is failing specifically in cylinder 1. The ECM identifies the affected cylinder by correlating crankshaft deceleration with camshaft position. The fact that only cylinder 1 is misfiring narrows the cause to parts that are specific to that cylinder — its plug, coil, injector, compression, or in some cases its harness wiring.
What are the symptoms of P0301 on a 2012 Toyota Tacoma?
Check Engine Light steady or flashing depending on misfire severity. Distinct rough idle that smooths out at higher RPM. Stumble or hesitation under acceleration. Reduced engine power. Smell of unburned fuel from the exhaust. Faint exhaust pop or backfire on overrun in severe cases
What causes P0301 on a 2012 Toyota Tacoma?
Failed ignition coil on cylinder 1 (most-common). Worn, fouled, or wrong-gap spark plug in cylinder 1 (most-common). Clogged, leaking, or electrically failed injector on cylinder 1 (common). Burnt exhaust valve or low compression on cylinder 1 (occasional). Damaged or chafed wiring to the cylinder 1 coil or injector (occasional). Cracked cylinder 1 intake runner or local vacuum leak (rare)
Is it safe to drive a 2012 Toyota Tacoma with P0301?
No. P0301 is a high-severity code on the 2012 Toyota Tacoma — avoid driving until it is diagnosed and repaired, as it can indicate an unsafe condition or risk further damage.