P0301 on a 2012 Jeep Wrangler
Cylinder 1 Misfire
P0301 on a 2012 Jeep Wrangler 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 Jeep Wrangler?
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 Jeep Wrangler generation — the symptoms, causes, and diagnostic steps below apply to every model year from 2010 through 2014.
Is it safe to drive a 2012 Jeep Wrangler with P0301?
No. P0301 is a high-severity code on the 2012 Jeep Wrangler — 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 Jeep Wrangler?
- 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 Jeep Wrangler?
| 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 Jeep Wrangler
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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 Jeep Wrangler
Owner-reported safety complaints and official recalls filed with the U.S. National Highway Traffic Safety Administration for the 2012 Jeep Wrangler. Use these to gauge how common a problem is on your specific vehicle before you start chasing Jeep Wrangler diagnostics.
- POWER TRAIN 282
- ENGINE 171
- STEERING 204
- ELECTRICAL SYSTEM 147
- AIR BAGS 128
10 active recalls
- AIR BAGS:FRONTAL:PASSENGER SIDE:INFLATOR MODULE Jan 2019
Chrysler (FCA US LLC) is recalling certain 2010 Dodge Ram 3500, Ram 4500/5500, 2010-2011 Dodge Dakota, 2010-2014 Dodge Challenger, 2010-2015 Dodge Challenger, Chrysler 300, and 2010-2016 Jeep Wrangler vehicles. Upon deployment of the driver's frontal air bag, excessive internal…
NHTSA campaign 19V018000 - SEAT BELTS:FRONT:ANCHORAGE Sep 2019
Chrysler (FCA US LLC) is recalling certain 2011-2018 Jeep Wrangler right hand drive vehicles. The driver's seat belt buckle mounting strap may fracture and separate from the seat frame.…
NHTSA campaign 19V680000 - AIR BAGS:FRONTAL:PASSENGER SIDE:INFLATOR MODULE Jan 2018
Chrysler (FCA US LLC) is recalling certain 2009-2013 Jeep Wrangler, Chrysler 300, Dodge Challenger and Dodge Charger vehicles, and 2009-2011 Dodge Dakota vehicles sold, or ever registered, in the states of Alabama, California, Florida, Georgia, Hawaii, Louisiana, Mississippi, Sou…
NHTSA campaign 18V021000 - AIR BAGS:FRONTAL:PASSENGER SIDE:INFLATOR MODULE May 2016
Chrysler (FCA US LLC) expanded the affected population to include 73,712 2005-2009 RAM 2500 trucks produced at the St. Louis North Assembly Plant. With this change, Chrysler is recalling certain model year 2004-2008 RAM 1500, 2005-2009 RAM 2500, 2006-2009 RAM 3500, 2007-2010 RAM…
NHTSA campaign 16V352000
How do I fix P0301 on a 2012 Jeep Wrangler?
- 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 Jeep Wrangler
The 2010-2014 Jeep Wrangler was commonly sold with the following powertrains: 3.6L Pentastar V6, 2.0L Turbo I4, 3.0L EcoDiesel V6. Common trims include Sport, Sport S, Sahara, Rubicon.
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 Jeep Wrangler: frequently asked questions
What does diagnostic trouble code P0301 mean on a 2012 Jeep Wrangler?
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 Jeep Wrangler?
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 Jeep Wrangler?
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 Jeep Wrangler with P0301?
No. P0301 is a high-severity code on the 2012 Jeep Wrangler — avoid driving until it is diagnosed and repaired, as it can indicate an unsafe condition or risk further damage.