P0241

Code

Generic P — Powertrain

Turbocharger/Supercharger Boost Sensor B Circuit Low

Brand: Generic

Type: P — Powertrain

Views: UK: 37 EN: 158 RU: 47

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Page language: EN

Causes

Faulty boost/charge pressure sensor (sensor B)
Short to ground on the sensor B signal wire
Open or high-resistance wiring/connectors in the sensor B circuit
Corroded or damaged connector pins at sensor or ECU
Failed sensor reference voltage (5V) or sensor ground
Intermittent wiring fault (chafed harness, water intrusion)

Symptoms

Check Engine MIL illuminated
Reduced engine power or limp mode (reduced boost)
Poor acceleration or hesitation under boost
Surging or inconsistent boost control
Lower fuel economy
Possible black smoke under heavy load if fueling rich to compensate

What to check

Read and record freeze frame and live data with a scan tool; compare sensor B to sensor A (if present)
Visually inspect sensor connector, wiring harness, and nearby components for damage, corrosion, or water
Backprobe the sensor B connector to measure signal voltage with key ON and engine running
Check for proper reference voltage (typically ~5 V) at the sensor connector
Check sensor ground continuity to engine/ECU ground
Measure continuity and resistance of signal wire to ECU pin; check for short to ground

Signal parameters

Typical sensor output (MAP/boost) signal range: about 0.5–4.5 V (varies by manufacturer)
Low-fault condition: signal near 0 V or below manufacturer threshold (often
Reference supply: ~5.0 V from ECU (verify exact spec for vehicle)
Ground: good chassis/engine ground continuity
Resistance: signal wire should show continuity to ECU pin; no short to ground (near 0 Ω) or high open-circuit

Diagnostic algorithm

Retrieve codes and review freeze frame data; confirm P0241 is active and note conditions.
Compare live boost/pressure readings from sensor B to sensor A (if present) and to expected values at idle and boost.
Perform a visual inspection of sensor B, connector, and wiring for obvious damage, corrosion, or water ingress.
With ignition ON (engine OFF), backprobe the sensor connector: verify reference voltage (~5 V) and ground circuit. If missing, investigate ECU power/ground circuits.
With engine running, measure sensor B signal voltage. If signal is near 0 V or well below expected, check for short to ground on the signal wire (disconnect sensor and measure wire to ground).
If a short to ground is found, isolate and repair wiring (replace harness, repair splice, protect from rubbing).
If wiring checks good, bench-test or substitute a known-good sensor B and re-check live data for normal signal range.
If a replacement sensor cures the fault, clear codes and road test to confirm. If fault returns, proceed to inspect ECU connector and perform continuity/voltage checks at ECU.
If wiring and sensor are good but fault persists, consider ECU diagnostic procedures or repair/reprogram as per manufacturer guidance.
After repairs, clear codes and verify proper operation under varied load conditions.

Likely causes

Damaged or corroded connector at boost sensor B
Sensor B internal failure (shorted output transistor)
Signal wire contacting chassis ground or other grounded component
Poor sensor ground or missing 5V reference from ECU
Wiring harness damaged in areas that move or rub

Fault status

⚠️ Status

Stored when the PCM/ECM detects a lower-than-expected voltage from the Turbocharger/Supercharger Boost Sensor B circuit (signal below defined threshold). This can indicate a short to ground, failed sensor, open circuit, or loss of reference/ground. 'B' designates the secondary boost pressure sensor/circuit.

🟡 Repair difficulty: Medium

⏱️ Diagnostic time: 0.5-2 hours (varies by vehicle complexity and accessibility)