OBD-II Code
P3424
Severity
Not yet reviewed
Nobody on our side has assessed this code yet, so we are not going to guess at how serious it is.
Can you drive it
We cannot say
Treat it as unknown until a shop reads it with live data. If the check-engine light is FLASHING, stop driving as soon as it is safe to — that means an active misfire, whatever the code.
Indicative cost (USD)
$40–$4,500
From this code's diagnostic notes. Varies by vehicle, diagnosis, parts, and local labor. This is not a repair quote.
P3424 means the ECM commanded cylinder 8 to deactivate and the performance feedback didn't match.
How a shop works this
Work from evidence to part, not the other way round. A code names a circuit or a symptom; it does not name the part that failed.
Note every code that is set, not just this one.
Codes that appear together usually narrow the cause faster than any one of them read alone.
Read the freeze frame — the conditions the fault was recorded under.
Cold or warm, idle or load, road speed and engine speed. A fault that only appears cold is a different fault from one that only appears under load, even with the same code on the scanner.
Confirm the fault is current rather than history.
Clear the code and see whether it returns under those same conditions. A code that does not come back may have been logged during a repair, a flat battery, or a bad connection that has since been disturbed.
Then follow the diagnostic notes further down this page, in the order they are written.
They are written in the order a shop works this code, cheapest checks first. Where they name a component, inspect its wiring and connector before replacing it.
If the code comes back after a repair, the underlying fault is still there. That is the point to bring in a scanner with live data and freeze-frame, or a shop that has one.
Common symptoms
- Check engine light
Read the full diagnostic procedureP3424 means the ECM commanded cylinder 8 to deactivate and the performance feedback didn't match.
P3424 means the ECM commanded cylinder 8 to deactivate and the performance feedback didn't match.
Cheapest-first ladder
- confirm cylinder 8's bank assignment (Chrysler Hemi: cyl 8 passenger-side rear, GM LS-based V8: cyl 8 passenger-side rear, Ford modular V8: cyl 8 passenger-side rear) — cylinder 8 is the back-of-the-passenger-bank position on virtually every modern V8, which means longest exhaust manifold heat exposure plus longest oil-feed-gallery run.
- Ohm the cylinder-8 MDS/AFM solenoid across the two pins (8 to 15 ohms cold = healthy), backprobe for the ECM's 0.5 to 1.5A activation pulse, and scan oil pressure at the deactivation gallery (25 to 65 psi at 1500+ rpm needed for clean lifter collapse).
- Watch the cylinder-8 misfire counter during the deactivation window.
- Cylinder 8 is statistically the most likely V8 position to throw a deactivation code because it sees the highest heat soak, longest oil gallery, and last spot in the deactivation rotation.
- The expensive misdiagnosis: Chrysler 5.7/6.4 Hemi MDS lifters are the actual problem on 80% of P3400-P3424 codes, and cylinder 8 is the canonical Hemi-tick failure position — listen at the passenger-side valve cover with a stethoscope before condemning the solenoid.
- Replacing the solenoid on a collapsed-lifter engine fixes only 20% of cases.
Vehicle-specific patternsChrysler 5.7L Hemi (RAM 1500 2009-current, Charger/Challenger R/T 2005-current, Grand Cherokee, Durango, 300C) throws P3424 more than any other deact…
Chrysler 5.7L Hemi (RAM 1500 2009-current, Charger/Challenger R/T 2005-current, Grand Cherokee, Durango, 300C) throws P3424 more than any other deactivation code because cylinder 8 is the canonical Hemi-tick failure position — passenger-side rear, longest oil gallery, highest heat soak. Any P3424 on a 100k+ mile Hemi should start with a stethoscope on the valve cover and a borescope inspection through the spark-plug hole before any solenoid swap. 6.4L Hemi SRT (392 Charger/Challenger, Grand Cherokee SRT, Durango SRT) shares the failure mode at accelerated wear rates and compounds it with higher cylinder pressures. GM AFM 5.3L L83 (Silverado/Tahoe/Suburban 2014+), 6.0L (Avalanche/Yukon XL), and 6.2L L86/L87 (Silverado/Sierra/Tahoe/Yukon 2014+) throws cylinder-8 AFM codes when the AFM oil-pressure-relief-valve sticks open and gallery pressure drops below activation spec; AFM-delete kits at $1,800-$3,200 installed are the GM permanent fix and many GM techs recommend doing the delete preemptively before the first lifter failure. Ford 6.2L Boss V8 (F250-F350 SuperDuty, F150 Raptor) and 5.0L Coyote (Mustang GT, F150) throw VCT-equivalent codes from phaser screen clogging. Honda VCM J35 V6 doesn't apply. Hemi lifter + roller cam rebuild runs $2,500-$4,500 parts + 12-16 hr labor.
Estimated repair$40 to $4,500.
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