Is my turbo failing with P0238?

Unlikely — "circuit high" is an electrical signal fault. The turbo itself is only implicated by mechanical codes (over/underboost) or physical symptoms.

Can I drive with P0238?

The car typically limits boost, so it's driveable but flat. Extended limp-mode driving is safe for the engine but unpleasant.

Sensor or wiring — how do I know?

Key-on engine-off: if the reading is pegged high, unplug the sensor. Reading changes = sensor side; unchanged = wiring/ECU side.

Engine / Turbo · Generic OBD-II

P0238 — Turbocharger Boost Sensor A Circuit High

The boost-pressure sensor signal is pegged above its valid range — an electrical fault in the sensor, its wiring, or the connector, not usually the turbo itself.

By iCarsoft Engineering Team Updated July 2, 2026 Checked against SAE J2012

Quick reference

Severity

Medium

Safe to drive

Caution

System

Engine / Turbo

Code type

Generic

Repair level

DIY-Moderate

Typical cost

$50–$500

Circuit-high codes are electrical by definition — this is a multimeter-and-connector job far more often than a turbo job.

What triggers it

Common causes, most likely first

Failed boost pressure (MAP) sensor

Internal failure drives the signal to the rail — the most frequent cause.

Very common

Signal wire shorted to voltage

Chafed insulation lets the signal touch a 5 V or 12 V feed.

Common

Corroded or damaged connector

Bent pins and green crust fake out-of-range readings.

Common

Open ground to the sensor

A lost ground floats the output high.

Occasional

ECU input fault

Rare, diagnosed by elimination.

Less common

How it shows up

Symptoms you'll notice

Reduced power / limp mode — the ECU limits boost with an untrusted sensor.
Check Engine light — often immediate and steady.
Implausible boost readings — pegged high on live data.
Sluggish turbo response — conservative control strategy.

How to pinpoint it

Diagnostic steps

Read the boost sensor on live data, key-on engine-off

It should match barometric pressure (~100 kPa). Pegged high with the engine off = electrical fault confirmed.Tool: live data

Inspect connector and wiring

Unplug, check pins for corrosion/bending, wiggle-test the harness while watching the reading.Tool: visual + live data

Verify 5 V reference and ground

Back-probe: reference present, ground good, signal within range.Tool: multimeter

Compare against BARO/MAP

Cross-check with the engine's other pressure sensors at key-on — they should agree.Tool: live data

Replace the sensor

With wiring proven, the sensor is the fix.Tool: hand tools

What the fix costs

Repair & cost

Boost/MAP sensor

$60–200

Usually top-of-manifold access

Wiring repair

$80–250

Chafe/short repairs

Diagnosis

$100–150

One shop hour

Estimates are indicative and vary by region, vehicle and parts choice. Confirm the actual cause with live data before buying parts.

Diagnose it yourself

The right iCarsoft tool for P0238

iCarsoft CR Pro S

The key-on sensor-vs-barometric comparison that cracks P0238 is a ten-second check on CR Pro S live data — and wiggle-testing while graphing catches intermittent wiring faults a static meter misses.

Full-system scanLive data graphingBi-directional testsService resets

View iCarsoft CR Pro S Compare tools

Coming soon

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Enter your make, model and what you're seeing — the iCarsoft AI assistant will rank the likely causes for your car and suggest the next test.

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Quick answers

P0238 FAQ

Is my turbo failing with P0238?: Unlikely — "circuit high" is an electrical signal fault. The turbo itself is only implicated by mechanical codes (over/underboost) or physical symptoms.
Can I drive with P0238?: The car typically limits boost, so it's driveable but flat. Extended limp-mode driving is safe for the engine but unpleasant.
Sensor or wiring — how do I know?: Key-on engine-off: if the reading is pegged high, unplug the sensor. Reading changes = sensor side; unchanged = wiring/ECU side.

P0238 — Turbocharger Boost Sensor A Circuit High