Can you keep driving?
Can you keep driving?
Stop driving if any of these apply
- !The engine starts stalling, losing power sharply, or refusing to respond to throttle normally.
- !The check-engine light flashes or the vehicle suddenly runs much worse after the code appears.
What to check first
Step-by-step checks
- 1
Free - no tools
Inspect the boost sensor connector and harness for looseness, corrosion, or heat damage
- 2
Free - no tools
Check the small hose or reference line if the system uses one
- 3
Basic tool needed
Compare the live boost reading with engine behavior at idle and under light load
- 4
Basic tool needed
If the code appeared after intake or turbo work, confirm the sensor line is routed correctly
- 5
Basic tool needed
If other boost-related codes are present, treat them as one system fault
If the code returns
- -If the reading is implausibly high on a cool engine, an open circuit or sensor drift is more likely.
- -If the hose is blocked or routed wrong, fix that before replacing the sensor.
- -If the code returns after replacement, check the feed, ground, and hose path again.
Background
What this code means
P0238 is a generic OBD-II code for a high-input turbocharger boost sensor A fault.
That means the ECU is seeing a pressure reading above what it expects, which can happen because of an open circuit, a sensor fault, or a hose/reference issue.
Diagnosis
Common causes
Open boost sensor circuit
A break in the signal path can make the reading high.
Failed boost sensor
The sensor may drift or fail internally.
Blocked or misrouted reference line
A hose issue can make the sensor report too much pressure.
Harness damage
Heat or vibration can open the circuit over time.
Avoid these mistakes
What not to do
- xDo not replace the sensor or pump first if there is obvious wiring, connector, or intake damage.
- xDo not ignore drivability changes or stalling just because the code sounds electrical.
Parts
Parts that may need replacing
See also
Related OBD codes
P0234
P0234 usually means the turbo or supercharger is producing too much boost.
P0235
P0235 usually means boost sensor A has a circuit malfunction.
P0236
P0236 usually means boost sensor A is out of range or performing poorly.
P0237
P0237 usually means boost sensor A is reading too low.
P0239
P0239 usually means boost sensor B is out of range or performing poorly.
Source notes
Generic OBD-II (SAE J1979 / ISO 15031-5). P0238 was expanded around common high-input boost-sensor faults, especially open circuits, sensor drift, and hose routing problems.
This guide is written as a generic multi-make reference, so bulletin history, sensor locations, and repair order can still change by manufacturer and engine family.
This is generic OBD-II guidance and should not override vehicle-specific service information. Exact diagnosis and repair steps vary by make, engine family, and model year.
Last reviewed: 2026-04-10
Reference: Open reference