P023E

Code

Generic P — Powertrain

Manifold Absolute Pressure - Turbocharger/Supercharger Boost Sensor B Correlation

Brand: Generic

Type: P — Powertrain

Views: UK: 17 EN: 30 RU: 31

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Page language: EN

Causes

Failed or intermittent MAP Sensor B
Damaged wiring or poor connector connection (open, short to voltage, short to ground)
Intake or boost leak between turbo and sensor
Faulty boost control solenoid, wastegate, or bypass valve causing unexpected boost
Contaminated or clogged sensor port
PCM/ECM software or internal fault

Symptoms

Malfunction Indicator Lamp (MIL) illuminated
Reduced engine power or limp-home mode
Poor acceleration, turbo lag or surging
Black smoke (diesel) or rich running condition under boost
Unstable idle or stalling in some cases

What to check

Read and record freeze-frame and live data for MAP Sensor B and any other MAP/boost sensors
Visually inspect sensor, connector, and wiring harness for damage, corrosion or oil contamination
Compare MAP Sensor B output to MAP Sensor A (if present) and to commanded boost during key engine conditions
Backprobe sensor connector: verify reference voltage (typically 5 V), ground continuity, and sensor signal voltage
Use a calibrated boost/vacuum gauge to confirm actual manifold/boost pressure
Inspect intake tract, intercooler and hoses for leaks, loose clamps or damage (pressure or smoke test recommended)

Signal parameters

Sensor supply/reference commonly 5.0 V ±0.1 V; check at harness pin with key on
Sensor signal typically about 0.5 V at high vacuum to ~4.5 V at high boost (varies by sensor and vehicle)
Expected MAP idle values commonly ~30–45 kPa (≈9–13 inHg) depending on engine and elevation
Under boost, MAP should rise above atmospheric (~100 kPa) according to turbocharger command; significant mismatch between Sensor A and B often >10–20 kPa (or >0.5–1.0 V) is suspicious
Sensor resistance (where specified) should match manufacturer spec; no short to ground or battery

Diagnostic algorithm

Retrieve all stored codes and freeze-frame data. Note operating conditions when code set (RPM, load, temperature).
Perform visual inspection of MAP Sensor B, connector and wiring for damage, pin corrosion or oil intrusion.
With key ON engine OFF, backprobe sensor: verify reference voltage (typically 5 V) and good ground. If reference missing, trace to fuse/PCM.
Start engine and monitor live MAP B signal. Compare to MAP A (if present) and to a handheld boost gauge. Look for correlation during idle, snap throttle and sustained load.
Wiggle wiring harness while monitoring signal to identify intermittent open/shorts.
Perform smoke or pressure test on intake/intercooler system to identify boost leaks that could cause low or inconsistent readings.
Test boost control components: actuators, wastegate and solenoid operation. Verify commanded vs actual boost behavior.
If wiring and system checks OK and sensor signal out of spec, replace MAP Sensor B. Use OEM or equivalent sensor and verify connector pinout.
Clear codes and road test under the same conditions that originally set the code. Re-scan for recurrence.
If code persists after sensor replacement and wiring verified, suspect PCM fault or require manufacturer-specific diagnostics/updates.

Likely causes

MAP Sensor B electrical fault (connector corrosion, broken wire)
MAP Sensor B out of specification or contaminated
Intake tract or intercooler leak causing differing pressures
Boost control component (wastegate/solenoid) malfunction
Reference 5 V supply or ground problem to the sensor

Fault status

⚠️ Status

P023E — MAP (Turbo/Supercharger) Boost Sensor B Correlation: MAP Sensor B signal does not match expected boost or reference sensor; check sensor, wiring, intake leaks and boost control components.

🟡 Repair difficulty: Medium

⏱️ Diagnostic time: 1.0-3.0 hours