Code
P0419
GWM
P — Powertrain
- Intake manifold relay B fault
AI status
Completed
Completed
100%
Causes
- Defective intake manifold relay (Relay B)
- Blown fuse supplying the relay circuit
- Open, shorted or corroded wiring or connector in the relay control or power circuit
- Poor or missing ground at the relay or intake runner actuator
- Faulty intake manifold runner actuator/solenoid
- ECM driver output fault or internal failure
Symptoms
- Malfunction Indicator Lamp (MIL) illuminated
- Reduced engine performance or hesitation at certain RPMs
- Rough idle or unstable idle speed
- Reduced fuel economy
- Possible limp-home mode or reduced power in some vehicles
- Intake manifold runner position not changing (no actuator movement)
What to check
- Read freeze frame and pending codes with a capable scan tool; note related intake runner or actuator codes
- Visually inspect relay, fuse, connectors and wiring for damage, corrosion or overheating
- Verify fuse continuity and proper fuse rating on the relay feed circuit
- Swap the relay with an identical known-good relay (if accessible) to check function
- Backprobe relay coil and switched terminals to confirm battery voltage and control signal when commanded
- Check for proper ground at the relay and at the intake manifold runner actuator
Signal parameters
- Battery feed to relay: ~12 V with ignition ON (should be near battery voltage)
- Relay control signal from ECM: switches between ~0 V (ground) and open/high depending on design when commanded
- Relay coil resistance: measurable low-ohm continuity (typical relays show tens to low hundreds of ohms); coil should not be open circuit
- Switched output to actuator: ~12 V present when relay is energized
- Actuator response: actuator current draw should be within manufacturer expected range (no excessive current indicating short or mechanical seizure)
Diagnostic algorithm
- Connect a scan tool, record freeze frame and live data. Confirm P0419 is present and note any related codes.
- Perform a visual inspection of the relay, fuse, wiring harness and intake manifold runner actuator connector for damage or corrosion.
- Check and replace any blown fuses related to the intake manifold/runner circuit.
- With ignition ON, measure battery voltage at the relay feed terminal; verify presence of full battery voltage.
- Command the intake runner system with the scan tool while backprobing the relay coil and switched terminals. Confirm the ECM issues the expected control signal and that the relay clicks and passes voltage to the actuator.
- If the relay does not operate, swap with a known-good identical relay and re-check operation.
- If the relay clicks but the actuator does not move, measure voltage at the actuator connector and check actuator resistance/current. Inspect for mechanical seizure or binding in the runner mechanism.
- Check continuity from relay output to actuator and inspect for shorts to ground or battery.
- If wiring and actuator are good, test the ECM output driver for correct switching; if ECM output is missing or abnormal, consider ECM fault or replacement after confirming wiring integrity.
- Repair or replace faulty relay, fuse, wiring, connector, or actuator as indicated. Clear codes and perform a road test to confirm repair. Re-scan to ensure P0419 does not return.
Likely causes
- Relay failure or relay contact sticking
- Loss of power or ground to the relay (fuse, connector, wiring)
- Open/short in the ECM control circuit to the relay
- Faulty intake manifold runner actuator loading the circuit
- Connector corrosion or poor pin contact
Fault status
Status
P0419 — Intake manifold relay B fault: ECM detected abnormal operation or circuit fault in intake manifold runner relay B (open/short/failed relay or wiring).
Repair difficulty: Medium
Diagnostic time: 0.5-2.0 hours
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