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Home / DTC / P0238 — Turbocharger / supercharger boost sensor A - high circuit

P0238 — Turbocharger / supercharger boost sensor A - high circuit

Detailed page for trouble code P0238.

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Code

P0238

LAND ROVER P — Powertrain

Turbocharger / supercharger boost sensor A - high circuit

Brand: LAND ROVER
Type: P — Powertrain
AI status
Completed
ready
Completed 100%
Page language: EN

Causes

  • Boost/pressure sensor A defective
  • Signal wiring shorted to battery/5V reference
  • Poor connector contact or corroded pins
  • Blocked, crushed or disconnected sensor reference/pressure hose (if sensor is pitot/remote)
  • Faulty ground or 5V reference at sensor
  • Faulty boost control components causing actual overboost (wastegate, bypass, boost control solenoid)

Symptoms

  • Malfunction Indicator Lamp (MIL) illuminated
  • Reduced engine power or limp mode
  • Erratic boost behavior or unexpected surging/overboost symptoms
  • Poor acceleration or hesitation under load
  • Possible increased smoke or abnormal engine noises under boost
  • Diagnostic trouble code present in engine control module

What to check

  • Read and record freeze-frame and live data with a capable scan tool (boost pressure, MAP, commanded vs actual boost)
  • Visual inspection of sensor, connector, wiring harness for damage, corrosion, or pin push-out
  • Inspect pressure reference hose(s) for blockages, kinks, disconnections or routing errors
  • Check for other related codes (boost control solenoid, wastegate solenoid, MAP sensor codes)
  • Backprobe sensor connector to measure supply voltage, signal voltage and ground continuity with key ON engine OFF
  • Compare sensor signal to engine vacuum/boost measured with a calibrated mechanical pressure gauge

Signal parameters

  • Typical MAP/boost sensor supply: ~5.0 V reference (key ON)
  • Typical sensor signal output range: ~0.5–4.5 V depending on design (0.5 V ~ vacuum, 4.5 V ~ high boost)
  • Fault condition: signal at or near supply voltage (close to 5 V) or outside expected voltage range for operating conditions
  • Monitor live boost reading vs commanded boost; ECU may flag high when signal exceeds programmed threshold

Diagnostic algorithm

  1. Connect a professional scan tool and read stored/frozen data; note conditions when DTC set (load, RPM, temperature).
  2. Visually inspect sensor, connector and harness for damage, corrosion, melted insulation or water ingress. Repair as necessary.
  3. With ignition ON (engine off) backprobe connector: verify 5V reference present, good ground, and sensor signal voltage. If reference or ground missing, trace wiring to ECU and repair.
  4. If signal is near battery/reference voltage, disconnect sensor: if voltage on signal circuit remains high, suspect wiring short to power; if signal drops to open-circuit value, sensor is likely bad—replace sensor.
  5. With sensor reconnected, start engine and compare boost reading on scan tool to an independent mechanical boost gauge. If scan tool shows abnormally high boost but mechanical gauge is normal, suspect sensor or wiring. If mechanical gauge confirms high boost, investigate wastegate/boost control solenoid and actuator for binding or control faults.
  6. If wiring and sensor bench/voltage tests pass, perform a continuity and resistance check from sensor connector to ECM connector to rule out intermittent shorts/opens. Repair/replace harness as needed.
  7. If all electrical and mechanical checks are normal and the replacement sensor produces the same code, consider ECM diagnosis or replacement per manufacturer procedures.
  8. Clear codes and test drive to verify repair; monitor for recurrence and confirm live sensor values are within expected range.

Likely causes

  • Damaged sensor connector or pin shorted to power
  • Sensor internal failure (output stuck high)
  • Pressure reference hose blocked or routed to high pressure source
  • Faulty boost control solenoid or stuck wastegate causing real high boost
  • Open/poor ground or intermittent wiring making the sensor read high

Fault status

⚠️ Status
ECM detected turbo/supercharger boost sensor A signal higher than allowed. Possible sensor failure, short to power, wiring/connector fault, or actual overboost. MIL set; driveability may be reduced.
🟡 Repair difficulty: Medium
⏱️ Diagnostic time: 1.0-3.0 hours

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413

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