← Misfire / rough running on all engines

Symptoms · 6.2 Boss (gas)

6.2 Boss (gas): misfire, rough idle, hesitation or surging

2 documented failures on this engine list this among their signs. They are ordered from the most widespread down. Each one shows the signs in its record's own words, how to tell it from the others, the usual fix and any recall or bulletin.

1. Ignition service wear (16 plugs / coils) Common
2. Exhaust valve seat wear (early builds) Occasional

Not sure which engine you have, or want the recalls for your exact truck? Check your VIN: it names the engine and lists the campaigns for that model year. Whether a recall is still open on your VIN: nhtsa.gov/recalls.

1 Ignition service wear (16 plugs / coils)

aggregated How widespread: Common

How it shows up

• rough idle / misfire as plugs age - doubled service surface (16 plugs per engine)

Its other signs

• plug access and condition vary by bank; coils fail individually

How to tell it apart

• service both plugs per cylinder as sets on an aged engine
• test coils on a miss before replacing hardware in bulk

Usual fix

service: plugs (x16) + coils as wear parts

Root cause, parts and sources →

2 Exhaust valve seat wear (early builds)

aggregated How widespread: Occasional

How it shows up

• progressive rough idle and misfires that worsen when hot

Its other signs

• low / uneven compression across cylinders on early-build engines
• valve lash drifting out of spec between services

How to tell it apart

• compression / leak-down test per cylinder, hot and cold
• check valve lash and recorded idle quality before teardown
• on confirmed recession: head service with updated exhaust seats

Usual fix

head service with updated exhaust-valve-seat hardware; verify the machine shop installs the updated seats

Root cause, parts and sources →

Other symptoms on the 6.2 Boss (gas)

Ticking, knocking, rattle or whine

Everything on the 6.2 Boss (gas)Its recalls and bulletins

Order: how widespread each failure is in its record (near-universal, very common, common, occasional, rare), then the number of NHTSA owner complaints that match its keywords. Complaint counts are keyword matches, not a manual review of each complaint. A symptom listed here means the failure is documented with that sign; it is not a diagnosis of your truck. Tiers: verified, aggregated, contested, data-gap. How we tier and source facts.