P0308 on RAM: How to Diagnose & Fix
Cylinder 8 Misfire Detected
3 RAM models · 5 documented issues · 5 critical · $200-$12,000 repair
P0308 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 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.
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Sources for this issue (3)
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)
The 5.7L Hemi V8 uses Multi-Displacement System (MDS) hydraulic lifters to deactivate four cylinders during light-load cruising. The MDS lifters are known to fail, causing a persistent ticking noise (the infamous "Hemi tick") and misfires on the deactivated cylinders. When an MDS lifter collapses or sticks, it cannot properly deactivate and reactivate the valve, leading to a dead cylinder. In severe cases, a failed lifter can damage the camshaft lobe, requiring a complete top-end rebuild.
Common Symptoms
- Persistent ticking noise from engine that does not change with temperature
- Misfire on one or more cylinders (P0300 series codes)
- Check engine light
- Rough idle
- Loss of power under acceleration
- Ticking intensifies during MDS cylinder deactivation mode
How to Fix
Replace all 16 lifters (8 MDS and 8 standard) with either OEM or upgraded non-MDS lifters. Many owners delete the MDS system entirely using a non-MDS camshaft, standard lifters, and an MDS delete tuner/programmer — this eliminates the failure mode at the cost of 1-2 mpg. If the camshaft has been damaged, it must be replaced during the lifter job. This is a significant repair requiring intake manifold removal and valley pan access.
Sources for this issue (4)
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)
P0308 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 P0308 mean on a RAM?
P0308 stands for "Cylinder 8 Misfire Detected." P0308 means the engine computer detected a misfire on cylinder number 8 — that cylinder is failing to combust properly or at the correct time. The PCM identifies it by monitoring crankshaft speed variations as cylinder 8 fires. Misfires waste fuel, increase emissions, and can overheat and damage the catalytic converter, so a hard misfire may cause a flashing check engine light. Typical symptoms include rough idle, vibration, hesitation, and reduced power. On RAM it is documented across 3 models: 1500, 1500 Classic, 2500.
What are the most common causes of P0308?
The most common causes of P0308 are: Worn, fouled, or incorrectly gapped spark plug on cylinder 8, Failed ignition coil or coil-on-plug for cylinder 8, Faulty, clogged, or leaking fuel injector, Vacuum or intake air leak affecting that cylinder, Low compression (worn rings, burnt/leaking valve, head gasket), Damaged spark plug wire or boot (on applicable engines), Carbon buildup or sticking valve. The specific cause varies by vehicle.
How much does it cost to fix P0308 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 P0308 on a different make?
View P0308 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.