P0300 on Dodge: How to Diagnose & Fix
Random/Multiple Cylinder Misfire Detected
10 Dodge models · 15 documented issues · 9 critical · $40-$15,000 repair
P0300 on Dodge by model: symptoms, diagnosis and fix
HEMI engines with Multi-Displacement System (MDS) can develop a ticking noise from the MDS lifters. This is most noticeable at idle and during light acceleration. While often not immediately harmful, it can indicate lifter wear.
Common Symptoms
- Ticking noise at idle
- Tick that follows engine RPM
- Noise louder when warm
- Tick comes and goes
- Sound from top of engine
How to Fix
Use quality synthetic oil meeting Chrysler MS-6395 spec. MDS delete kit available for permanent solution. Some owners have had lifters replaced under extended warranty. Regular oil changes help minimize tick.
What you need to fix it
Only diagnosis- and fitment-reviewed repair parts are linked here.
- Mopar 53022263AF 5.7L HEMI MDS/VVT camshaft
Replace only when inspection shows lifter-related lobe damage Fitment: Verified 5.7L branch; not the 6.4L camshaft Live OEM direct product page when checked
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Sources for this issue (2)
HEMI engines with Multi-Displacement System (MDS) can develop a ticking noise from the MDS lifters. This tick is most noticeable at idle and during light acceleration. While often not causing immediate damage, it can indicate lifter wear that may eventually require attention.
Common Symptoms
- Ticking noise at idle
- Tick that follows engine RPM
- Noise louder when engine is warm
- Tick comes and goes
- Noise from top of engine
How to Fix
Use quality synthetic oil meeting the spec in your owner's manual (Chrysler MS-6395 for the 5.7L; MS-12633 0W-40 for the 6.4L). Consider MDS delete kit if desired permanent solution. Some owners have had lifters replaced under extended warranty. Regular oil changes help minimize tick.
What you need to fix it
Only diagnosis- and fitment-reviewed repair parts are linked here.
- Genuine Mopar 53022298AB Multiple Displacement Solenoid
Replace only when testing shows the solenoid/control branch is faulty rather than a collapsed lifter or worn cam Fitment: 2010-2024 5.7L/6.4L MDS applications per live title; confirm the vehicle actually has MDS Live direct US performanc…
Sources for this issue (2)
The 3.6L Pentastar V6 can develop a ticking noise often related to the rocker arms or hydraulic lifters. This is common on engines with higher mileage or irregular oil change intervals. Some early Pentastar engines had rocker arm design issues that were later updated.
Common Symptoms
- Ticking noise at startup
- Tick that varies with RPM
- Noise from valve cover area
- Check engine light with misfire codes
- Rough idle in severe cases
How to Fix
Use quality synthetic oil and change regularly. If tick is severe, rocker arms may need replacement with updated design. Some owners have had success with engine flush treatments. Check for TSBs related to your model year.
Sources for this issue (1)
Some 2015-2021 Dodge Challenger 5.7L and 6.4L engines can develop a persistent engine-speed-related tick, rough idle, loss of power, or misfire from hydraulic roller-lifter, roller, or cam-lobe wear. A tick alone does not prove internal wear: exhaust-manifold leakage, injector noise, oil-pressure concerns, and other causes must be ruled out. MDS fitment is transmission-specific, not engine-name-wide: automatic 5.7L and 6.4L applications use cylinder deactivation, while six-speed manual applications are non-MDS. Cam and lifter wear is not limited to MDS hardware.
Common Symptoms
- Ticking noise at idle
- Tick more prominent on cold start
- Noise from top of engine
- Rough idle
- Loss of power
- Engine misfire
How to Fix
Retrieve DTC and misfire data, localize the noise, and check for exhaust-manifold leakage before buying internal parts. If cam/lifter wear is suspected, inspect the lifter rollers and cam lobes and check the VVT oil-control-valve screen for metal debris. Use the lifter type that matches the factory transmission/MDS configuration and verify by VIN. On an automatic-MDS car, non-MDS lifters are only one part of a complete engineered mechanical delete with compatible cam/supporting parts and calibration. Correct oil and electronic MDS disabling do not repair a worn lifter, roller, or camshaft.
What you need to fix it
Only diagnosis- and fitment-reviewed repair parts are linked here.
- Genuine Mopar 5038785AD front MDS hydraulic lifters and yoke pack
Front-position MDS lifter pack for a confirmed MDS valvetrain repair after the heads are removed and roller/cam damage is inspected Fitment: Live fitment lists 2009-2023 Challenger 5.7L/6.4L, but the year-specific catalog specifies MDS/f…
- Genuine Mopar 5038786AD rear MDS hydraulic lifters and yoke pack
Rear-position companion pack for a complete factory-MDS lifter repair Fitment: Live fitment lists 2009-2023 Challenger 5.7L/6.4L; pair with the front packs only on a verified MDS engine, and confirm that two front plus two rear packages …
- Genuine Mopar 5038784AD complete non-MDS HEMI lifter/yoke bundle
Complete lifter branch for a factory non-MDS/manual-transmission 5.7L or 6.4L after cam and roller inspection confirms replacement Fitment: Live bundle explicitly contains 16 lifters and four yokes and lists 2015-2023 Challenger 5.7L/6.4…
- Genuine Mopar 53022372AA 5.7L MDS/VVT camshaft
Camshaft replacement when lifter-roller failure has visibly or measurably damaged a lobe on the verified 5.7L MDS engine Fitment: Year-specific catalogs identify this as the 5.7L MDS cam; direct fitment lists 2009-2023 Challenger 5.7L. D…
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Sources for this issue (3)
A P0420 ("Catalyst System Efficiency Below Threshold, Bank 1") or P0430 ("Bank 2") check-engine light is one of the most common emissions codes on the Dodge Challenger, especially on higher-mileage V8 cars. The PCM sets the code when it compares the upstream (pre-cat) and downstream (post-cat) oxygen-sensor signals: if the downstream sensor begins to mimic the rapidly-switching upstream sensor instead of staying relatively flat, the computer concludes the converter is no longer storing/releasing oxygen efficiently. On the Challenger this code is frequently NOT a worn-out converter at all. The two most common upstream root causes are (1) an exhaust leak from broken exhaust-manifold bolts — the well-documented "HEMI tick" on the 5.7L and 6.4L V8s — which lets atmospheric oxygen into the exhaust stream and confuses the rear O2 sensor, and (2) a long-running misfire (worn plugs, failing coils, leaking injectors on the 3.6L Pentastar) that dumps raw fuel into the converter and physically destroys it over time. A failed downstream O2 sensor, contaminated converter (from an oil-cooler/oil-filter-housing leak on the Pentastar), or simply an aged/degraded cat round out the causes. Chrysler has also issued PCM software bulletins for P0420/P0430 — for example TSB 18-090-24 (superseding 18-086-19) for 2019 Challengers with the 5.7L HEMI, which names PCM software as the cause — so a PCM reflash should be ruled out before any hardware is replaced. Because the converter sits in the federal/CARB emissions-warranty window for many of these cars, the diagnosis order matters a lot to the owner's wallet.
Common Symptoms
- Check Engine Light on with stored code P0420 (Bank 1) and/or P0430 (Bank 2)
- Vehicle may run normally with no obvious driveability change at first
- Failed state emissions / smog inspection
- Possible rotten-egg (sulfur) smell from a degrading converter
- Slight loss of power or fuel economy if the converter is partially clogged
- Often accompanied by a cold-start exhaust tick (broken manifold bolts) on the V8
- Code returns shortly after clearing if root cause is not fixed
How to Fix
Diagnose before you spend. (1) Pull all stored codes first — if any misfire (P0300-P030x) or O2-sensor codes are also present, fix those first, since a misfire will quickly kill a new converter. (2) Inspect for exhaust leaks, especially broken exhaust-manifold bolts on the 5.7L/6.4L V8 (look for soot/ticking at the manifold flanges); repair the leak and clear the code before condemning the cat — a manifold leak is a very common false-trigger of P0420 on the HEMI. (3) Check for a PCM software update at the dealer (e.g., TSB 18-090-24 for the 2019 5.7L), which addresses P0420/P0430 codes set by PCM software. (4) Graph the oxygen sensors with a scan tool: the downstream (Bank 1 Sensor 2 / Bank 2 Sensor 2) signal should be slow and steady; if it copies the fast-switching upstream sensor, the converter is failed. A failing downstream O2 sensor is a much cheaper part to try than a converter. (5) Only after ruling out leaks, misfires, software and sensors should the catalytic converter be replaced. Use an OEM Mopar or quality CARB-compliant aftermarket (e.g., MagnaFlow) unit; cheap universal cats often re-trigger the code. On the 3.6L Pentastar, also confirm the oil-filter-housing/oil-cooler is not leaking oil into the system, as that contamination will destroy a new converter. Note: the converter is covered under the federal 8-year/80,000-mile emissions warranty (and 7-year/70,000-mile high-priced-parts coverage in California) on many of these model years — check before paying out of pocket.
What you need to fix it
Only diagnosis- and fitment-reviewed repair parts are linked here.
- OBDLink MX+ Bluetooth OBD-II adapter with included apps
Graph upstream and downstream oxygen-sensor behavior and fuel-trim data after misfires and exhaust leaks are repaired, before condemning a converter Fitment: Generic OBD-II live-data tool; confirm the app exposes the required PIDs on the…
- Genuine Mopar 5149180AB oxygen sensor
Sensor branch only when waveform, heater-circuit and wiring tests identify the exact failed sensor rather than converter inefficiency Fitment: Live fitment lists 2011-2023 Challenger 3.6L/5.7L/6.2L/6.4L, but catalog position varies by ye…
- MagnaFlow 16420 OEM-grade federal/EPA direct-fit catalytic converter assembly
Confirm engine family and local emissions rules $911.90 with Add to Cart on the live US retailer page when checked
- Genuine Mopar 6509863AA exhaust-manifold stud
Repair an identified 5.7L manifold fastener leak before evaluating converter efficiency again Fitment: 2009-2020 Challenger 5.7L side-position stud, sold individually; other engines and positions require their own hardware $11.65 and Add…
- Fel-Pro MS97083 exhaust-manifold gasket set
Reseal a confirmed 5.7L manifold-to-head leak before interpreting catalyst-monitor data Fitment: 5.7L HEMI branch only after vehicle fitment confirmation; not the 6.1L/6.2L/6.4L gasket $56.99 and Add to Cart on the live AutoZone US produ…
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Sources for this issue (2)
The production valve springs on the 6.4L 392 HEMI can crack or fracture. A weakened spring can cause a persistent single-cylinder misfire that remains after plug, coil, or injector swaps; a complete fracture can let the valve contact the piston and cause major cylinder-head or engine damage. High-RPM and modified/cammed use changes valvetrain load, but the correct replacement spring must be selected from the camshaft's lift and required installed/open pressures rather than from boost alone.
Common Symptoms
- Persistent single-cylinder misfire that does NOT go away after replacing spark plugs, coil packs, or injectors
- Rough idle, stuttering, and a shaking/vibrating engine
- Check engine light flashing under load (active misfire)
- Loss of power and the car going into limp/reduced-power mode
- Low compression on the affected cylinder during a compression or leak-down test
- Ticking, clattering, or valvetrain noise from one bank
- In a full failure: severe knocking, loss of a cylinder, then catastrophic engine failure (dropped valve)
- Symptoms most often appear after track use, hard high-RPM driving, or on modified/cammed/boosted cars
How to Fix
Stop driving if a broken spring is suspected. Confirm the fault with compression or leak-down testing and valve-cover inspection before buying parts. For affected 2021-2022 Challenger/Charger 6.4L vehicles, FCA GPOP bulletin 9004444 directs technicians to replace all valve springs after a broken spring is confirmed, not only the failed spring; other model years should follow the current VIN-specific service procedure. The OEM production repair uses sixteen 5037382BC springs. Mopar Performance 68277306AA is an individual higher-lift spring: a full 6.4L engine requires sixteen plus correctly sized shims, and the spring must match the camshaft's lift and pressure requirements. Aftermarket PAC/BTR/Comp/Livernois sets should likewise be selected to the cam manufacturer's specification.
What you need to fix it
Only diagnosis- and fitment-reviewed repair parts are linked here.
- High Horse Performance bundle of 16 genuine Mopar 5037382BC production valve springs
Full-engine production-spring repair after compression/leak-down and valve-cover inspection confirms a broken or weakened spring Fitment: 2011-2023 Challenger 6.4L 392 HEMI subset in this issue; the live title extends through 2024 and ex…
- Mopar Performance 68277306AA beehive valve spring
Modified/cammed engine branch only when the camshaft manufacturer specifies this spring's lift and pressure characteristics Fitment: One spring; sixteen plus correctly sized shims are required for a full 6.4L engine, and this must not be…
- OTC 5609 cylinder leakage tester kit
Confirmation tool before buying valve-spring parts; distinguishes valve leakage from rings, cylinder walls or head-gasket leakage Fitment: Universal professional test tool with 14 mm hose and 10/12/18 mm adapters; requires a regulated co…
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Sources for this issue (2)
P0300 code reference
General diagnostic-code context. The code alone does not confirm a cause for your vehicle; use the applicable issue card and its sources.
Frequently asked questions
What does P0300 mean on a Dodge?
P0300 stands for "Random/Multiple Cylinder Misfire Detected." P0300 means the engine computer detected misfires occurring randomly or across multiple cylinders rather than in one specific cylinder. A misfire is when a cylinder fails to ignite its fuel-air mixture properly, which the computer senses through small fluctuations in crankshaft speed. Because it's not isolated to one cylinder, the cause is usually something that affects the whole engine — like fuel, air, or ignition system problems — rather than a single coil or plug. Persistent or heavy misfiring wastes fuel, runs rough, and can damage the catalytic converter, which is why a flashing check engine light should be taken seriously. On Dodge it is documented across 10 models: Durango, Charger, Challenger, Intrepid, Ram 1500, Stratus, Grand Caravan, Journey, Viper, Neon.
What are the most common causes of P0300?
The most common causes of P0300 are: Worn or fouled spark plugs (across cylinders), Vacuum or intake air leak, Weak fuel pump, clogged fuel filter, or low fuel pressure, Failing ignition coils or worn spark plug wires, Dirty or faulty mass airflow (MAF) sensor, Clogged or dirty fuel injectors, Faulty crankshaft/camshaft position sensor, Low compression or EGR/PCV system faults. The specific cause varies by vehicle.
How much does it cost to fix P0300 on a Dodge?
Published repair estimates on Dodge range from $40 to $15,000 depending on the model and root cause. If an issue mentions a recall or campaign, check your VIN with the manufacturer or NHTSA and confirm eligibility and coverage with a dealer.
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Content compiled with AI assistance using NHTSA complaints, TSBs, and owner reports. May contain errors. Always verify with your vehicle's service manual.