OBD-II Code
P3403
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)
$30–$400
From this code's diagnostic notes. Varies by vehicle, diagnosis, parts, and local labor. This is not a repair quote.
$30 (harness repair) to $400 (solenoid + labor).
P3403 means the ECM detects the cylinder-1 deactivation/intake-valve-control solenoid circuit pulled to ground when it shouldn't be — either the harness is shorted to chassis ground, the solenoid coil has shorted internally, or the ECM driver itself has failed in the on-state.
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 procedureP3403 means the ECM detects the cylinder-1 deactivation/intake-valve-control solenoid circuit pulled to ground when it shouldn't be — either the harn…
P3403 means the ECM detects the cylinder-1 deactivation/intake-valve-control solenoid circuit pulled to ground when it shouldn't be — either the harness is shorted to chassis ground, the solenoid coil has shorted internally, or the ECM driver itself has failed in the on-state.
Cheapest-first ladder
- disconnect the solenoid and clear the code, then re-test — if the code returns with the solenoid disconnected, the short is in the harness between the solenoid and the ECM; if the code clears, the solenoid coil is internally shorted.
- Ohm the disconnected solenoid across the two pins — healthy is 8 to 15 ohms cold, anything below 5 ohms is a partial short that pulls excess current and triggers low-circuit codes.
- Inspect the harness for chafing against the valley plate edge, the intake manifold studs, or the cylinder-head casting near the spark-plug wells (heat-cycle damage cracks the wire insulation).
- Backprobe with the ignition on, engine off, and check for unexpected ground continuity on the signal wire — any reading below 100 ohms to chassis ground confirms a wiring short.
- The expensive misdiagnosis: Chrysler 5.7/6.4 Hemi MDS lifters are the actual problem on 80% of P3400-P3424 codes, but circuit-low codes like P3403 are almost always electrical — pulling a valve cover on a true P3403 wastes 4 hours and finds nothing.
Vehicle-specific patternsChrysler 5.7L Hemi (RAM 1500 2009-current, Charger/Challenger R/T 2005-current, Grand Cherokee, Durango, 300C) frequently throws P3403 on cylinder 1…
Chrysler 5.7L Hemi (RAM 1500 2009-current, Charger/Challenger R/T 2005-current, Grand Cherokee, Durango, 300C) frequently throws P3403 on cylinder 1 when the MDS harness chafes against the front edge of the valley plate under the intake — the cylinder-1 solenoid sits at the front of the driver's bank and has the shortest harness run, which paradoxically makes it the most prone to chafing because it has the least slack. 6.4L Hemi SRT (392 Charger/Challenger, Grand Cherokee SRT, Durango SRT) shares the same harness routing. GM AFM 5.3L L83 (Silverado/Tahoe/Suburban 2014+), 6.0L (Avalanche/Yukon XL), and 6.2L L86/L87 (Silverado/Sierra/Tahoe/Yukon 2014+) sets a circuit-low code when the lifter-oil-manifold (LOM) harness shorts to the cylinder-head casting through a worn grommet — $30 in fresh grommets and a harness re-routing fixes it. Ford 5.0L Coyote VCT-i (Mustang GT, F150) sets a similar low-circuit code when the VCT solenoid pintle sticks open and the ECM reads continuous current draw. Honda VCM J35 V6 (Pilot, Odyssey, Ridgeline, Accord V6) typically doesn't set P3403 directly but throws ROCV-circuit codes that present the same way; VCM disable harness at ~$120 is the band-aid, ROCV solenoid replacement is the real fix.
Estimated repair$30 (harness repair) to $400 (solenoid + labor).
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