P0249

Code

Generic P — Powertrain

Turbocharger/Supercharger Wastegate Actuator B Low

Brand: Generic

Type: P — Powertrain

Views: UK: 24 EN: 35 RU: 27

AI status

Completed

ready

Completed 100%

Page language: EN

Causes

Open or shorted wiring in wastegate actuator B control circuit
Poor connector contact (corrosion, bent pins, contamination)
Faulty wastegate actuator or boost control solenoid (stuck, internal short)
Vacuum or boost line leak (for vacuum-actuated systems)
Mechanical binding or seized wastegate linkage
Blown fuse or faulty power/ground supply to actuator/solenoid

Symptoms

MIL (Check Engine Light) illuminated
Reduced engine power or limp mode
Poor acceleration or hesitation under boost
Unstable or incorrect boost pressure (overboost or underboost)
Unusual turbo noises or hissing from boost/vacuum leaks
Possible increased fuel consumption or smoke

What to check

Read freeze frame and live data: commanded vs actual wastegate position, actuator control duty or voltage, and boost pressure
Scan for additional related DTCs (boost sensor, turbo control solenoids, MAF/MAP)
Visually inspect actuator, solenoid, connectors, and wiring for damage or corrosion
Inspect vacuum/boost hoses and clamps for cracks, disconnection, or leaks
Wiggle test wiring and connectors while monitoring live data or lamp status
Check fuses and power/ground supply to actuator/solenoid

Signal parameters

Control signal: typically a PWM duty cycle 0-100% (varies by system) or a variable 0–12 V command depending on design
Expected resting/idle signal: near 0% duty or 0–1 V when not commanded (system dependent)
Resistance of actuator/solenoid: typically in the tens of ohms range (consult vehicle spec; wide variation possible)
Boost pressure: compare commanded boost vs actual boost (kPa or psi); significant deviation indicates control issue
Continuity: low resistance path to ECM ground/power expected; open circuit indicates wiring fault

Diagnostic algorithm

Retrieve DTC freeze frame and note operating conditions (load, RPM, temp). Clear codes and attempt to re-run to confirm repeatability.
Inspect actuator/solenoid connector and wiring for damage, corrosion, or loose pins. Repair any damaged harness or connector issues.
With connector disconnected, check for proper supply voltage and ground at the actuator/solenoid connector using a DMM. Compare to vehicle wiring diagram.
Measure coil/actuator resistance. If resistance is open or shorted to ground/power, replace the actuator/solenoid.
Use a scan tool to command the actuator/solenoid while observing live data (duty cycle/voltage) and verify actuator movement or response. If no response but correct command present, suspect actuator or wiring between ECM and actuator.
Perform a wiggle test on wiring while commanding actuator to reproduce fault; repair any intermittent wiring faults.
Inspect and test vacuum/boost hoses and wastegate linkage for leaks or binding. Free or replace stuck linkage and replace damaged hoses.
If electrical supply and actuator bench tests are good but fault persists, inspect ECM grounds and related control circuitry. Consider ECM testing/replacement only after eliminating wiring and actuator faults.
After repairs, clear codes and perform a road test under load to confirm boost control and that the DTC does not return.

Likely causes

Damaged or chafed wiring harness to actuator
Corroded/loose connector at actuator or ECM
Failed actuator/solenoid (electrical or mechanical failure)
Vacuum/pressure hose disconnected or split
Wastegate linkage fouled with carbon or stuck

Fault status

⚠️ Status

P0249 — Turbocharger/Supercharger Wastegate Actuator B Low. The ECM has detected a low or missing control/signal from the wastegate actuator B circuit. May cause reduced power or improper boost control. Inspect actuator, wiring, connectors, and vacuum/boost lines.

🟡 Repair difficulty: Medium

⏱️ Diagnostic time: 1.0-2.5 hours