P0305 on RAM: How to Diagnose & Fix
Cylinder 5 Misfire Detected
3 RAM models · 7 documented issues · 6 critical · $200-$12,000 repair
P0305 on RAM by model: symptoms, diagnosis and fix
The 5.7L HEMI engine with Multi-Displacement System (MDS) can experience premature lifter and camshaft wear. The MDS deactivation lifters are prone to failure, causing ticking, misfires, and in severe cases, camshaft lobe damage. This issue has led to class action lawsuits.
Common Symptoms
- Ticking noise at idle
- Engine misfire codes P0300-P0308
- Check engine light
- Loss of power
- Rough idle
- Tick worse when cold
How to Fix
For early detection: Use quality synthetic oil and change every 5,000 miles. Install an MDS delete kit ($200-400) to prevent future failures. If lifters have failed: Full lifter replacement with non-MDS lifters ($2,000-3,500). If camshaft is damaged, expect $3,500-5,500 for full repair. Consider a tuner to disable MDS electronically.
Owner tips & cautions
- TipDIY repairs can save significantly - dealer charges $200-400 but DIY costs are typically 50-70% less
- TipInstall an MDS delete kit ($200-400) to prevent future failures.
- WarningThis is a high-severity issue - ignoring it can lead to costly repairs or safety concerns. Address it promptly.
Sources for this issue (5)
On the 3.6L Pentastar V6, the needle bearings inside the roller rocker arms fail, letting the rocker go loose and hammer/score the camshaft lobe. This produces a distinct top-end tick ('Pentastar tick') and, if left, camshaft damage and misfires. It is a widely reported failure across Ram 1500, Wrangler, Grand Cherokee, and Durango; Chrysler revised the rocker part several times to improve needle-bearing durability, so a repeat failure is common if an outdated rocker is installed.
Common Symptoms
- Ticking/tapping from valve cover area
- Check engine light
- Random misfire
- Rough running
- Loss of power
How to Fix
Remove the valve cover and inspect rockers for play and cam lobes for scoring. Replace failed rocker arms (both intake and exhaust as needed) with the latest-revision part, and replace the camshaft if lobes are scored. Because debris circulates, inspect lifters/lash adjusters and change oil. TSB 09-002-14 REV. B addresses P0300 from excessive cylinder leakage that may require left cylinder head replacement. Always use the newest rocker revision to avoid a repeat.
What you need to fix it
Only diagnosis- and fitment-reviewed repair parts are linked here.
- Genuine Mopar 5184296AH valve rocker arm
Confirm VIN for 2021-2024 rather than extending this link.
- Genuine Mopar 5184332AA valve lash adjuster
Seller lists 2011-2025 Mopar applications including Ram 1500; confirm the 3.6L VIN and quantity before order.
- 5184378AG right exhaust camshaft for early Pentastar
2013-2018 Ram 1500 3.6L stated by seller; right exhaust only, 5184378AG family. Not a later eTorque cam or another bank/position.
- Genuine Mopar 5047912AD later 3.6L intake camshaft
Confirm bank, VIN and current supersession.
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Sources for this issue (2)
On 2003-2008 5.7L HEMI engines the cylinder-head valve-seat bores were machined without sufficient interference fit. Combined with localized coolant boiling and hot spots in the heads, an exhaust or intake valve seat can spin loose and drop into the combustion chamber. When the seat drops it is hammered by the valve and piston, causing a sudden misfire, loss of power, a heavy metallic knock, and in many cases destruction of the piston, valve and head. This is distinct from the well-known exhaust-manifold-bolt tick and the later MDS lifter/cam failure; it is a structural cylinder-head defect specific to pre-2009 (pre-Eagle) HEMIs. Overheating events dramatically raise the risk. The 2009 Eagle HEMI revision used improved seat material and tighter machining and largely eliminated the failure.
Common Symptoms
- Sudden single-cylinder misfire (P0301-P0308)
- Loud metallic knocking or clattering
- Significant loss of power
- Rough idle and shaking
- Check engine light flashing
- History of an overheating event before failure
How to Fix
There is no patch repair for a dropped seat. The affected cylinder head (often both) must be replaced or rebuilt with upgraded seats; if the piston or valvetrain is damaged, a long-block or complete engine replacement is required. Owners keeping a pre-2009 HEMI should avoid overheating, maintain the cooling system rigorously, and address any cooling-system weakness or persistent misfire (P0301-P0308) immediately. When replacing one head, many shops replace both heads plus the timing set and oil pump, which are also known weak points on this engine family.
What you need to fix it
Only diagnosis- and fitment-reviewed repair parts are linked here.
- Spartan 2DK1L remanufactured left 5.7L cylinder head
Confirm 2003-2004 separately, VIN, EGR provision, casting and core terms.
- Genuine Mopar 53021616BA early 5.7L cylinder head
Verify VIN, side and casting before order.
- Fel-Pro 260-3145 full engine gasket set
2003-2008 Dodge Ram 1500 5.7L V8 as listed; confirm included head gaskets and obtain the correct new head-bolt sets separately.
- Mopar 53021581AC non-VVT timing-chain set
2005-2008 5.7L non-VVT HEMI; seller explicitly says it does not fit 2009+ VVT engines. Confirm the 2003-2004 application separately.
- Genuine Mopar 53021622AF early 5.7L oil pump
Verify VIN and pickup/front-cover compatibility.
As an Amazon Associate, we earn from qualifying purchases; other part links may also earn au7o a commission. Confirm fitment by VIN before buying.
Sources for this issue (3)
Early-production 2025 RAM 1500 trucks equipped with the new 3.0L Hurricane twin-turbocharged inline-six (Standard Output 420 hp and High Output 540 hp) are widely reported to throw check-engine lights and random/multi-cylinder misfire codes, often on cold start or under load in hot weather. Owners on the 5thGenRams and RamForum communities report P0300 (and per-cylinder P0301-P0306) within the first few thousand miles. Stellantis has issued multiple software TSBs (e.g., 08-055-25 for HO, 08-031-25 for SO, and a cold-start update) that reflash the ignition system control module (ISCM) and PCM; a separate TSB (09-025-25) addresses a purge-line/vacuum-leak source of lean misfires. This is a new-engine, new-generation problem outside the existing HEMI-focused coverage.
Common Symptoms
- Check engine light
- Engine misfire / stumble
- Rough idle
- Hesitation under acceleration
- Misfire codes on cold start
How to Fix
Have the dealer apply the latest ISCM/PCM software per the applicable misfire TSB (HO vs SO calibration). Inspect and reseat the EVAP purge line and the air-intake hose at the airbox for vacuum leaks (TSB 09-025-25). Many owners report running 91+ octane reduces misfire events in hot weather. If reflash and vacuum-leak repairs do not resolve it, dealer should diagnose ignition coils/injectors under powertrain warranty.
Sources for this issue (3)
Gas RAM 2500s with the 6.4L (392) HEMI V8 suffer a documented valvetrain defect in which the roller lifter needle bearings fail, the roller stops rolling and drags across the camshaft lobe, wiping out the lobe. The failure is linked to the truck's Multi-Displacement System (MDS/cylinder deactivation): when cylinders are deactivated, oil delivery to the affected lifters is restricted, starving the roller bearings. Owners report onset as a metallic 'HEMI tick' progressing to misfire, dropped cylinder and catastrophic top-end damage. A class-action lawsuit (Petro, et al. v. FCA US LLC, Case No. 1:22-cv-00621, whose named plaintiffs include a 2020 RAM 2500 owner) alleges FCA knew of the defect since at least 2012 and failed to disclose it. There is no safety recall, so repairs typically fall on the owner once warranty lapses.
Common Symptoms
- Metallic ticking/tapping from top of engine (HEMI tick)
- Engine misfire, rough idle
- Check engine light with misfire codes
- Loss of power / dropped cylinder
- Metal shavings in oil
- Loud knocking as failure progresses
How to Fix
Diagnosis via oil-analysis metal content, cylinder-specific misfire/lifter tick, and cam inspection. Accepted repair is replacement of all 16 lifters plus the camshaft (and any damaged pushrods/rockers); severely scored cams or circulated bearing debris often force a long-block or complete engine replacement. Many owners/shops disable/delete MDS during the rebuild to prevent recurrence. Frequent oil changes with correct-spec oil are the preventive measure.
What you need to fix it
Only diagnosis- and fitment-reviewed repair parts are linked here.
- Genuine Mopar 5045517AC 6.4L HD MDS camshaft
2014-2024 Ram 2500 6.4L Heavy Duty HEMI MDS as listed; confirm VIN and production data.
- Genuine Mopar 5038785AD front hydraulic lifters and yoke assembly
6.4L Heavy Duty HEMI with MDS; OE catalog requires quantity two front assemblies for the full engine. Confirm VIN, production date and required quantity.
- Genuine Mopar 5038786AD rear hydraulic lifters and yoke assembly
Confirm VIN and production date and do not treat one assembly as a complete set.
As an Amazon Associate, we earn from qualifying purchases; other part links may also earn au7o a commission. Confirm fitment by VIN before buying.
Sources for this issue (4)
The 5.7L HEMI with Multi-Displacement System (MDS) in the 1500 Classic develops lifter failure, particularly on cylinders that deactivate. The roller lifters can collapse or seize, causing ticking noise and misfires. This is the same issue as the standard 1500.
Common Symptoms
- Ticking or tapping noise from engine
- Misfire codes
- Check engine light
- Rough idle
- Loss of power on affected cylinder
How to Fix
Sources for this issue (1)
P0305 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 P0305 mean on a RAM?
P0305 stands for "Cylinder 5 Misfire Detected." This code means the engine control module detected a misfire on cylinder number 5, meaning that cylinder is not burning its air-fuel mixture properly on some combustion cycles. The computer senses misfires by watching for tiny fluctuations in crankshaft speed each time a cylinder fails to fire correctly. A misfire wastes fuel, can make the engine run rough or shake, and dumps unburned fuel into the exhaust, which can overheat and damage the catalytic converter. It generally points to a problem with spark, fuel delivery, or compression specifically affecting cylinder 5. On RAM it is documented across 3 models: 1500, 2500, 1500 Classic.
What are the most common causes of P0305?
The most common causes of P0305 are: Worn or fouled spark plug on cylinder 5, Failed ignition coil or coil pack for cylinder 5, Faulty or clogged fuel injector on cylinder 5, Vacuum or intake air leak affecting that cylinder, Bad spark plug wire or boot (on applicable engines), Low compression from worn rings, valves, or head gasket, Carbon buildup or sticking valve on cylinder 5, Lean or rich fuel condition affecting the cylinder. The specific cause varies by vehicle.
How much does it cost to fix P0305 on a RAM?
Published repair estimates on RAM range from $200 to $12,000 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.
Looking for P0305 on a different make?
View P0305 across all makes →Content compiled with AI assistance using NHTSA complaints, TSBs, and owner reports. May contain errors. Always verify with your vehicle's service manual.