P0238 OBD2 Trouble Code ▷ Check your Turbo Boost Sensor!

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P0238 OBD2 Trouble Code

Meaning of a P0238 Generic Code?

The technical definition of P0238 code is: Turbocharger Boost Sensor “A” Circuit High Input

In some Dodge and Chrysler vehicles, the definition of P0238 code is MAP Sensor Voltage Too High.

Whatever the case, this means the ECU is detecting a high voltage condition or open circuit in the boost sensor circuit. If the boost pressure voltage is greater than 4 volts even if no boost is required, the ECU instantly triggers the check engine light.

Pro Tip
The P0238 OBD2 trouble code usually means you have an issue with your Turbo Boost Sensor or other wiring issues. Grab your voltmeter and start testing. This is a pretty serious code, so if you’re not mechanically enclined I suggest getting it to your nearest trusted mechanic!

The turbo boost sensor is responsible for controlling the boost pressure inside the motor. If the ECU detects a high voltage, it will ignore the readings in boost sensor A and limit the fuel timing and boost pressure to a predetermined fail-safe mode. (Read more about boost sensors here: https://mechanicbase.com/engine/boost-pressure-sensor/)

Auto Repair Guys did a nice video showing how to troubleshoot this code on an Audi TT.


What are the causes of P0238 OBD2 Trouble Code?

boost pressue sensor
Boost pressure sensors can be the cause of a P0238 code! Image Source

In some cases, the DTC is triggered by a short circuit or frayed wiring in the turbo boost circuit. If you have a tuned or modified vehicle, this issue can be attributed to wiring problems in the turbocharger. (Here’s a run-down how to troubleshoot wiring harness problems)

Most of the time, a this DTC is caused by a faulty, dirty, or corroded turbo boost sensor. Make sure to verify the voltage of the boost sensor or remove any contaminants before ruling out a faulty sensor.


Related DTC codes: P0234, P0235, and P0238

P0238 fault code DTC explained

What are the symptoms of the P0238 DTC?

If the ECU reverts to limp mode, your vehicle will exhibit a noticeable lack of performance and acceleration. If the check engine light is ON and the P0238 code is showing on your OBD2 scanner, make sure to have the problem fixed at the soonest possible time.

Neglecting this code may not directly inflict damage to the motor, but it will lead to failure of the catalytic converter. And if you know anything about modern cars, replacing the catalyst does not come cheap!

Get this code fixed as soon as possible!

  • Poor engine performance
  • Loss of acceleration power
  • Check Engine Light illuminated

How much does it cost to fix a P0238 fault?

You will only spend around $60 to $100 in parts to fix the problem if it’s the Boost Pressure Sensor, but this all depends on vehicle type. Problems with the wiring harness or connectors in the turbo boost sensor are cheaper to fix (assuming your mechanic doesn’t spend lots of time diagnosing the faulty wire).

In rare cases, the generic OBD2 code is also related to a faulty ECU, which will cost hundreds or thousands of dollars to replace. If this happens, make sure to trace the source of the short to protect the new ECU from getting shorted internally.

A competent mechanic should check for technical service bulletins related to the make and model of your vehicle. In some cases, the manufacturer is already aware of the problem and will issue a fix to correct the problem.

You may also see codes like the P0299 or P0235 showing up if you have turbo boost issues.


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