P340A

Code

Generic P — Powertrain

Deactivation/Intake Valve Control Circuit Bank 1

Brand: Generic

Type: P — Powertrain

Views: UK: 20 EN: 26 RU: 14

AI status

Completed

ready

Completed 100%

Page language: EN

Causes

Open or shorted wiring in the intake valve deactivation circuit (bank 1)
Poor connection or corroded/loose connector at the solenoid/actuator
Faulty intake valve deactivation solenoid/actuator (stuck or coil failure)
Blown fuse or faulty relay supplying circuit power
Bad or intermittent ground
ECM/PCM driver fault

Symptoms

Malfunction Indicator Lamp (MIL) illuminated
Reduced engine performance or limp mode in some vehicles
Rough idle or intermittent misfire when deactivation is commanded
Decreased fuel economy if cylinder deactivation is affected
Unusual valve/train noise if the mechanism is mechanically stuck
Diagnostic trouble codes related to cylinder deactivation or cam control

What to check

Read freeze-frame and stored data with a scan tool; note conditions when fault set
Inspect wiring harness and connector for Bank 1 deactivation solenoid for damage, corrosion, or loose pins
Check battery voltage and charging system before tests (low voltage causes false faults)
Verify fuses and relays that feed the deactivation solenoid circuit
Back-probe connector with a scan tool or DVOM to observe command signal vs actual
Measure solenoid coil resistance and compare to vehicle specification

Signal parameters

Command signal: typically a switched 12V supply or PWM ground-driven output — expect a distinct ON/OFF or duty-cycle command from the PCM
When commanded ON: measured voltage at the solenoid power/ground should approach battery voltage or show the commanded PWM duty (vehicle-specific)
When commanded OFF: voltage should be near 0 V or open depending on driver type
Solenoid coil resistance: typically a low-ohm value (spec varies by manufacturer) — check service data for exact ohms
Continuity: low ohms between solenoid connector and ECM power/ground pins; high resistance or open indicates wiring break
Signal behavior: look for stable square wave or steady voltage corresponding to PCM command; erratic or absent signal indicates wiring/ECM fault

Diagnostic algorithm

Capture codes, freeze-frame and live data with a scan tool. Confirm P340A is current and note operating conditions.
Visually inspect harness and connector for bank 1 intake deactivation solenoid. Repair any obvious damage or corrosion.
Check fuses/relays and battery/charging voltage. Repair weak charging or blown fuse before further testing.
Back-probe solenoid connector while commanding deactivation ON/OFF. Verify PCM command signal appears and changes as expected.
Measure solenoid coil resistance with the connector disconnected. Compare to spec; replace solenoid if out of range or open.
Perform continuity test from solenoid connector pins to the ECM pins to detect opens or high resistance.
If command is present but solenoid does not respond, bench-test solenoid with appropriate voltage to confirm mechanical operation.
Wiggle test harness and connectors while monitoring circuit for intermittent faults. Repair chafing or loose terminals.
If wiring and solenoid are good and command signal is absent or incorrect, test ECM output driver; consult manufacturer procedures before replacing ECM.
After repairs, clear codes and perform a road/test procedure to verify the fault does not return.

Likely causes

Faulty deactivation solenoid/actuator
Open/short in harness or poor connector at solenoid
Corroded or loose ground or power feed
ECM output driver fault (less common)
Mechanical seizure or hydraulic failure preventing valve deactivation

Fault status

⚠️ Status

Deactivation/Intake Valve Control Circuit — Bank 1. Electrical fault detected (open/short/intermittent) on intake valve deactivation control circuit for bank 1.

🟡 Repair difficulty: Medium

⏱️ Diagnostic time: 1-3 hours