How to Diagnose and Fix a Misfire in Your 2012 Dodge Charger

How to Fix Misfire

A misfire in your 2012 Dodge Charger is a serious issue that can lead to poor performance, increased emissions, and potential damage to the catalytic converter. While the term "misfire" is a broad diagnostic trouble code (P0300-P0308), the root cause must be pinpointed. Based on direct feedback from owners of this specific model year, the path to a fix often involves methodical diagnosis rather than guessing, as many find the platform to be fundamentally reliable. As one owner, thatguyvenom69, shared about their 2012 Charger: "Reliability is amazing not any major issues yet." This suggests that when problems like a misfire do arise, they are often specific and solvable.

Symptoms

The most direct symptom of an engine misfire is the illumination of the check engine light. The vehicle's computer will store a specific code indicating a random misfire (P0300) or a misfire on a particular cylinder (P0301-P0308). You will likely feel this as a pronounced shaking or vibration, especially at idle or under acceleration. The engine may stumble, hesitate, or lack power when you press the gas pedal.

In some cases, the misfire may be severe enough to cause audible symptoms. Owners have reported hearing unusual "clunking" sounds from the engine bay. While a clunk could be related to various issues, when paired with a rough-running engine, it points toward a mechanical failure contributing to the misfire, such as a failing component in the valvetrain or accessory drive. Another symptom to watch for is visible smoke from the exhaust, which can indicate oil burning due to compromised piston rings or valve seals—a potential cause of a persistent misfire.

The drivability impact is significant. You may notice the car feels sluggish, fuel economy drops noticeably, and the transmission might shift erratically as the powertrain control module tries to compensate for the loss of power. It's crucial not to ignore these signs. As one owner, Wheres_Jay, asked regarding warning lights, "Can I just unplug the battery and reset?" While resetting the battery may temporarily turn off the light, it will not fix the underlying problem, and the code and symptoms will return.

Most Likely Cause

Based on aggregated owner discussions and the parts frequently mentioned, the single most likely cause of a misfire in the 2012 Dodge Charger is a failure within the ignition system or valvetrain, indirectly indicated by the mention of specific replacement parts like belts and thermostat housings in repair contexts. While a "belt" itself doesn't cause a misfire, the pursuit of fixing one often leads owners to discover related issues. For instance, during repairs for overheating (thermostat housing) or accessory drive problems (belt), underlying issues like a worn timing component or a compromised cylinder head can be uncovered, which directly lead to misfires.

The 5.7L HEMI V8 and 3.6L Pentastar V6 engines in this model year are robust, but high mileage can expose weaknesses. A common culprit on higher-mileage examples is wear on components like spark plugs, ignition coils, or, more seriously, issues with the valvetrain such as a stuck or failed valve lifter. The "clunking" sound reported by owners is a classic descriptor for a failing lifter or a problem with the Variable Valve Timing (VVT) system. When these components fail, they prevent a cylinder from sealing or firing properly, creating a persistent misfire.

How to Diagnose

Diagnosing a misfire requires a systematic approach to avoid replacing good parts. First, you need an OBD-II scanner. This tool is essential for reading the check engine codes. Don't just clear them; note the specific code. A P0304 code, for example, tells you cylinder 4 is misfiring. This narrows your search to one bank of the engine.

Start with the simplest possibilities. For the identified cylinder, perform a visual inspection. Check the spark plug wire (if equipped) or the ignition coil boot for damage or carbon tracking. Swap the ignition coil from the misfiring cylinder with one from a known good cylinder. Clear the codes, run the engine, and see if the misfire code follows the coil. If it does, you've found a bad coil. If not, move on. Remove and inspect the spark plug. Look for fouling (oil or fuel deposits), excessive wear, or a cracked porcelain insulator.

If basic ignition components check out, the diagnosis becomes more advanced. A compression test is the next critical step. This measures the engine's ability to build pressure in each cylinder. Low compression in the misfiring cylinder points to mechanical failure: worn piston rings, burnt or leaking valves, or a failed head gasket. A leak-down test can further pinpoint where the compression is escaping (intake valve, exhaust valve, or past the rings). Listening for a "clunking" or tapping noise with a mechanic's stethoscope can help locate a faulty lifter or rocker arm.

Step-by-Step Fix

This guide assumes you have diagnosed a misfire on a specific cylinder and traced it to a faulty ignition coil, a common and DIY-friendly repair. Always disconnect the negative battery terminal before beginning work.

Step 1: Safety and Preparation. Park on a level surface, engage the parking brake, and let the engine cool completely. Disconnect the negative battery cable. Gather your tools: a socket set, a spark plug socket with a rubber insert, and a torque wrench.

Step 2: Locate the Ignition Coil. Open the hood and locate the ignition coils. On the V8, they are mounted on top of the valve covers. On the V6, they are located at the front of the engine. Identify the coil for the misfiring cylinder (e.g., cylinder 4 is on the driver's side, second from the front).

Step 3: Remove the Coil. The coil is held by a single 7mm or 8mm bolt. Remove this bolt and set it aside. Firmly grasp the coil and pull it straight up and out of its well. It may require a slight rocking motion if it's stuck.

Step 4: Inspect and Replace. With the coil removed, inspect the rubber boot for tears or carbon arcing. It's often recommended to replace the spark plug while you have access. Insert the new coil by pushing it firmly down into the spark plug well until it seats completely. Hand-tighten the retaining bolt, then torque it to the manufacturer's specification (typically around 105 in-lbs or 9 Nm). Do not overtighten.

Step 5: Reconnect and Test. Reconnect the negative battery cable. Start the engine. The check engine light may remain on initially. Use your OBD-II scanner to clear the diagnostic trouble codes. Take the car for a test drive, ensuring it operates smoothly under acceleration. Monitor to see if the check engine light returns.

For more serious mechanical fixes, like addressing a "clunking" valvetrain noise, the process is far more intensive, involving removal of the valve cover and potentially the cylinder head. As one owner, Inner_Divide5833, noted about their 2012 AWD R/T, they were "trying to upgrade slowly." This mindset is key; address drivability issues like misfires before performance upgrades.

Parts and Tools Needed

• Ignition Coil: Mopar part #56029221AB is a common OEM replacement. Always confirm compatibility for your specific engine.
• Spark Plugs: For the 5.7L HEMI, use Champion RE16MCC5 or equivalent double-platinum plug. For the 3.6L Pentastar, use Champion 7989 or OEM equivalent. Replace in sets.
• Basic Hand Tools: Socket set (7mm, 8mm, 10mm, 13mm are most common), extensions, ratchet, torque wrench.
• Diagnostic Tools: A basic OBD-II code reader is the minimum. A more advanced scanner can monitor live data.
• Safety: Mechanic's gloves, safety glasses.
• For Advanced Repairs: Compression tester, leak-down tester, valve cover gasket set, and likely a full gasket kit if head removal is required.

Real Owner Costs

Repair costs vary dramatically based on the root cause. For a simple DIY fix like one ignition coil and a set of spark plugs, parts will cost between $100 and $200. Your labor is free.

If the issue is a failed lifter or related valvetrain work, costs soar. A shop repair for a HEMI "lifter tick" or failure often involves removing the cylinder head(s). Owners report quotes ranging from $2,500 to over $4,000 for this job, as it is labor-intensive and includes parts like lifters, pushrods, and head gaskets. As one owner considering a high-mileage 2012 SRT8 noted, "Its listed for $8,000." The potential cost of a major engine repair like this significantly affects the vehicle's value and total cost of ownership.

For reference, a professional diagnosis alone at a shop might cost $100-$200. Replacing all eight ignition coils and plugs at a dealership or independent shop could run between $600 and $1,000 in parts and labor.

Prevention

The best prevention for misfires is adhering to a strict maintenance schedule. Replace spark plugs at the manufacturer's recommended interval (typically every 30,000-100,000 miles depending on the type). Use high-quality fuel and consider periodic fuel system cleaner to prevent carbon buildup on intake valves, especially on direct-injection engines.

Regular oil changes are critical. Using the correct viscosity oil and changing it at or before the recommended interval is the best defense against valvetrain issues like lifter failure. Dirty or old oil loses its lubricating properties and can cause lifters to collapse. Listen to your car. Any new sound, like a tick, tap, or clunk from the engine, should be investigated promptly before it leads to a catastrophic misfire and more expensive damage.

What Owners Say

Real experiences from DODGE owners:

Owner Experiences

"2012 Dodge Charger R/T with 2023 4 scat pack piston brembos and 22” Jeep SRT8(replica) rims What’s your opinion will upload when I install the rears,I have them sitting ready and painted just don’t have the time install" — 2012RT_Charger (source)

"What’s your opinion will upload when I install the rears,I have them sitting ready and painted just don’t have the time install" — 2012RT_Charger (source)

"Tell me about your experiences. Been having fun with it since I bought it in March." — thatguyvenom69 (source)

Real Repair Costs

"Im wondering if this 2012 SRT8 with 95k miles on it is worth it. Its listed for $8,000." — Stxksy (source)

FAQ

Q: How long does it take to fix a simple misfire caused by a bad coil? A: For a competent DIYer, diagnosing and replacing a single ignition coil and spark plug takes about 30 minutes to an hour. This includes time to scan the code, locate the part, and perform the swap. A professional mechanic could do it in less time.

Q: Can I drive my Charger with a misfire? A: It is strongly advised not to. Driving with an active misfire can cause unburned fuel to dump into the exhaust system, destroying the catalytic converter—a repair that can cost over $1,000. It can also lead to further engine damage. The car may also enter a "limp mode" with severely reduced power.

Q: Is a misfire a common issue on the 2012 Charger? A: Based on owner reports, the 2012 Charger is generally considered reliable. However, like any high-performance or high-mileage vehicle, ignition components and valvetrain parts are wear items. Misfires are not a universal design flaw but become more probable as the vehicle ages and accumulates miles, especially if maintenance is deferred.

Q: DIY vs mechanic—what's recommended for a misfire? A: For simple ignition-related misfires (coils, plugs), DIY is very feasible and cost-effective with basic tools. If the diagnosis points to low compression, internal engine noises ("clunking"), or you are not comfortable with the diagnostic steps, taking it to a trusted mechanic is the wise choice. Misdiagnosis on internal engine problems can lead to wasted money on parts that don't fix the issue.

Q: Will disconnecting the battery reset a misfire code for good? A: No. As owner Wheres_Jay pondered, unplugging the battery will clear the code and turn off the light temporarily, but if the misfire condition is still present, the computer will detect it again within a few drive cycles and illuminate the light. This is a diagnostic step, not a repair.

Q: Could aftermarket modifications cause a misfire? A: Yes. While owners like 2012RT_Charger discuss upgrades like "scat pack piston brembos" and wheels, any modification that affects air, fuel, or spark without a proper tune can lead to drivability issues. If you've recently modified your engine and developed a misfire, the new components or the need for a professional tune should be your primary suspects.