P3451

Code

Generic P — Powertrain

Cylinder 7 Deactivation/Intake Valve Control Circuit Low

Brand: Generic

Type: P — Powertrain

Views: UK: 29 EN: 30 RU: 24

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Page language: EN

Causes

Damaged, corroded, or loose connector at the cylinder 7 intake valve solenoid
Open or shorted wiring (short to ground) between PCM and valve/solenoid
Failed intake valve actuation/deactivation solenoid (stuck or electrically shorted)
Blown fuse or faulty power/ground supply to the circuit
PCM driver fault
Low engine oil pressure or contaminated oil preventing valve actuator operation (mechanical/hydraulic systems)

Symptoms

Malfunction Indicator Lamp (MIL) illuminated
Rough idle or misfire feel localized to cylinder 7 under some conditions
Reduced engine performance or fuel economy
Possible unusual valve noise if actuator is mechanically stuck
Related drivability complaints during idle, low-speed or load changes

What to check

Read freeze frame and live data with a scan tool; note commanded vs actual valve/actuator status
Check for other stored codes (camshaft position, oil pressure, cylinder misfire codes)
Visually inspect connector and wiring at cylinder 7 solenoid for damage, corrosion, or oil intrusion
Backprobe the solenoid connector while monitoring voltage with the PCM commanding the actuator
Measure solenoid coil resistance (reference range below) with connector disconnected
Check fuses/relays and PCM ground for integrity

Signal parameters

Typical solenoid coil resistance: ~5–30 ohms (varies by application) — check OEM spec
Expected control voltage when actuated: near battery voltage (10–14 V) or PWM supply per manufacturer; low circuit indicates significantly lower than expected
If PCM uses low-side switching: commanded ON = near 0 V at coil return (ground) when measured to battery positive; expected OFF = battery voltage at supply pin
PWM control possible — frequency commonly low (several Hz) to high (up to hundreds of Hz) depending on design; duty cycle varies by command
Current draw when activated: typically hundreds of milliamps to a couple of amps depending on solenoid design

Diagnostic algorithm

Retrieve freeze-frame and note conditions when the code set (RPM, temp, oil pressure if available).
Clear the code, then attempt to reproduce while monitoring live data for the intake valve/actuator command and reported status.
Visually inspect the connector and harness at cylinder 7 for corrosion, bent pins, oil, heat damage, or chafing.
With ignition ON (engine off), backprobe the connector: verify supply voltage at the solenoid power pin (should be near battery if applicable) and verify PCM control pin behavior when commanding the solenoid via a scan tool.
Disconnect the solenoid and measure coil resistance against manufacturer spec. Infinite/open or very low/near 0 ohms indicates fault.
With connector disconnected, check for short to ground: measure resistance from the control wire to chassis ground; very low resistance suggests short-to-ground.
Command the solenoid using a scan tool while measuring voltage/current. Observe if voltage rises to expected levels or remains low.
Wiggle test wiring and connectors while monitoring live data to detect intermittent opens/shorts.
Swap the solenoid with an identical one from another cylinder (if available) to see if the code follows the component — only if safe and appropriate.
Check upstream fuses/relays and PCM ground points. If wiring and components test good, consider PCM driver fault and consult manufacturer repair information before replacing PCM.
If the system is hydraulically/oil operated, confirm proper oil level and pressure and inspect for mechanical binding of the actuator.

Likely causes

Corroded terminal or poor pin contact at the valve solenoid connector
Wiring chafed and shorting to ground near cylinder 7
Defective intake valve control solenoid on cylinder 7
Failed ground or supply circuit fused/relayed open upstream of solenoid

Fault status

⚠️ Status

Stored when the PCM detects a low-voltage or short-to-ground condition in the cylinder 7 intake valve deactivation/control circuit. May set the MIL and affect cylinder deactivation or valve timing/actuation.

🟡 Repair difficulty: Medium

⏱️ Diagnostic time: 0.5-2.0 hours