Comprehensive diagnostic guide for OBD-II code P0241

Turbocharger/Supercharger Boost Sensor B Circuit Range/Performance - Signal Too Low

What This Code Means

• What the code means: P0241 indicates an issue with the Turbocharger/Supercharger Boost Sensor B circuit. Specifically, the sensor B signal is reading below the expected range (Circuit Range/Performance). This is described in the open-source OBD-II code definitions as
  • Source alignment: Open Source OBD2 CODE DEFINITIONS (Turbo pressure sensor - Sensor B - Sinal muito baixo) / signal too low
• Where this code sits in the system: P0241 is a powertrain/engine control code used by OBD-II. Wikipedia's OBD-II article and the Powertrain Codes section classify such codes under the Powertrain category, reflecting that they pertain to engine/drive-train control systems that influence performance and emissions.
  • Source alignment: Wikipedia - OBD-II: Diagnostic Trouble Codes; OBD-II: Powertrain Codes

Symptoms

• Check Engine Light (MIL) illumination with P0241 stored or pending.
• Reduced or abnormally low turbo boost/engine power; difficulty maintaining highway speeds or passing.
• Hesitation, sluggish throttle response, or limp-mode-like behavior in some vehicles.
• Possible nuisance emissions-related concerns if the PCM targets incorrect boost readings.
• If other boost-related codes appear (e.g., P023x family), simultaneous symptoms may be more pronounced.

Most likely causes (probable distribution)

• Faulty Boost Sensor B (sensor itself) - ~40%
• Wiring harness or connector issues to sensor B (damaged wires, corroded pins, loose connectors) - ~25%
• Vacuum/boost leaks or intercooler/boost hose problems affecting sensed pressure (leaks cause low readings or stumble in boost delivery) - ~20%
• Boost-signal conditioning or sensor reference issues within the engine control module (ECM/PCM) or wiring that causes a low reading intermittently - ~5-10%
• Turbocharger actuator, wastegate, or related boost-control hardware faults causing actual low boost that the sensor then reports as low - ~5%

Diagnostic Approach

1) Confirm the code and gather data

• Use a scan tool to confirm P0241 is active and note any freeze-frame data: engine load, RPM, requested vs. actual boost (if the tool can show live boost sensor data), fuel trims, and other related DTCs that may provide context.
• Check for any other related boost codes (e.g., P023x family) that could complicate interpretation.

2) Visual inspection and basic electrical checks

• Inspect the Boost Sensor B wiring harness and connector: look for damaged insulation, chafed wires, corrosion, bent pins, or a loose/degraded connector.
• Inspect the grounding point and the sensor's reference/ground circuit; ensure there is a solid ground connection.
• Inspect the supply voltage (reference voltage, typically around 5V) and sensor signal wire with a multimeter or oscilloscope (back-probe while the engine is running or key-on, engine-off as permitted by the service procedure). Look for proper supply, a clean 0-5V signal range, and no short to ground or to supply.
• Check for any damage or oil contamination in the sensor area that could affect readings.

3) Sensor B integrity test (function test)

• If the vehicle's service information provides a spec, test Sensor B resistance/voltage against spec when possible.
• With the sensor unplugged, observe the PCM's fault response and live data. If the data changes to a baseline or safe value when unplugged, the sensor or its wiring is implicated; if it remains unchanged, the issue may be wiring/ECM-related.

4) Compare sensor readings to actual boost pressure

• If you have access to a mechanical boost gauge or an equivalent tool, compare the sensor B readings to measured boost pressure across RPM. A persistent discrepancy (low sensor reading vs. actual boost) indicates a sensor/wiring issue; actual low boost with a corresponding low sensor reading supports a mechanical boost problem.

5) Inspect boost system for leaks and mechanical issues

• Perform a smoke test or soapy-bubble vacuum/boost leak test on the intake tract, intercooler, pipes, and hoses to identify leaks that could cause low boost readings.
• Inspect intercooler for leaks or external damage; inspect hoses and clamps for tightness and integrity.
• Inspect turbocharger components and the boost-control pathway: wastegate actuator, vacuum/boost control solenoids, and associated hoses to ensure proper operation.
• If a mechanical fault (e.g., actuator stuck, failed wastegate) is suspected, diagnose with the manufacturer's service procedure and corrective actions.

6) Check boost control system and sensors

• If equipped, inspect the boost control solenoid (electrical connection, duty cycle control) and any related vacuum lines that actuate the wastegate or boost controller.
• Re-scan for any additional DTCs after clearing; see if P0241 returns or if new codes appear that point to other components (e.g., P0106/Map sensor readings, P0234/P0235 boost-related codes).

7) Electrical and ECM considerations

• If wiring and sensor appear sound, consider ECM-related checks per factory procedure (firmware version, known issues, re-flash if applicable). ECM faults are less common but possible causes when sensor readings are abnormally low without an obvious sensor or wiring fault.
• Ensure the vehicle's power supply and battery ground are solid; voltage dips can affect sensor readings.

8) Confirm and isolate

• After performing the above checks, clear codes and perform a road test with data logging. Observe whether P0241 returns, and verify the sensor B reading tracks correctly with actual boost, under varying engine load and RPM.

Repair Options

• Replace Boost Sensor B if the sensor is confirmed faulty (poor signal, out-of-range readings, or sensor failure).
• Repair or replace damaged wiring/connectors to Sensor B; fix pin corrosion, stuck pins, frayed wiring, or grounding issues.
• Repair boost leaks: replace cracked hoses, clamps, intercooler leaks, or damaged intercooler plumbing; ensure a tight and leak-free system.
• Repair turbo boost-control system: repair/replace faulty boost control solenoids, vacuum lines, and adjust/replace turbo actuator or wastegate mechanism as needed.
• If a PCM/ECM fault is identified: follow OEM procedures for reprogramming or replacement, including proper calibration and software updates.
• After repairs, re-scan, clear codes, and perform a validated test-drive to ensure P0241 does not return.

Safety Considerations

• Work with the engine off and the ignition off when inspecting electrical harnesses, then follow proper hot-work procedures if you must work near hot components.
• Be mindful of high-boost and high-pressure systems; relieve any residual pressure before disconnecting lines or hoses.
• Use appropriate PPE, keep hands clear of moving parts if the engine is started for diagnostic testing, and follow vehicle-specific safety guidelines.

Helpful references and notes

• Code classification and context: OBD-II diagnostic trouble codes and Powertrain Codes sections provide foundational understanding that P0241 is a powertrain-related DTC associated with boost system diagnostics.
  • Wikipedia references: OBD-II - Diagnostic Trouble Codes; OBD-II - Powertrain Codes
• Code definition (BOOSt sensor interpretation): Open Source OBD2 CODE DEFINITIONS lists the description for P0241 as which supports the interpretation that P0241 concerns the Sensor B boost-signal input and its range.
  • Source reference: OBD2 CODE DEFINITIONS

This diagnostic guide was generated using verified reference data:

• Wikipedia Technical Articles: OBD-II
• Open-Source OBD2 Data: N/A (MIT)

Content synthesized from these sources to provide accurate, real-world diagnostic guidance.

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