P0237 medium Severity

P0237: Turbocharger/Supercharger Boost Sensor "A" Circuit Low

Reduced engine power, possible limp-mode, decreased acceleration and fuel economy

Overview

P0237 indicates that the engine control module (PCM/ECM) has detected an abnormally low voltage signal from the turbocharger or supercharger boost pressure sensor "A" circuit, typically due to wiring faults, sensor failure, or pressure abnormalities affecting boost control.

Common Symptoms

  • Check engine light illuminated
  • Reduced engine power and acceleration
  • Poor fuel economy
  • Turbocharger or intake system noises (whistling/hissing)
  • Possible limp mode activation

Most Common Causes

Faulty boost pressure sensor "A" high

Sensor failing to send correct voltage signal to PCM under boost conditions.

Damaged or corroded wiring/connectors in sensor circuit high

Wiring harness shorts, opens, or poor connections often trigger low voltage readings.

Vacuum leaks or intake pressure loss medium

Leaks can reduce actual boost, mimicking low sensor voltage conditions.

Turbocharger mechanical fault medium

Failure in turbo housing or wastegate can cause actual low boost and erroneous sensor readings.

Faulty PCM/ECM low

Rare but possible; control module misinterpretation or internal failure of reference circuit.

Diagnostic Steps

  1. Confirm P0237 with an OBD-II scanner and review freeze frame data
    Expected: P0237 present without conflicting boost codes
    Interpretation: Verifies this specific fault to focus subsequent tests.
  2. Visually inspect boost sensor wiring and connectors for damage, corrosion, or loose pins
    Expected: No breaks, frays, or corrosion
    Interpretation: If issues present, repair wiring/connectors and retest.
  3. Back-probe sensor reference circuit with DVOM with key on engine off
    Expected: 5.0 V reference from PCM
    Interpretation: Absence indicates wiring or PCM reference circuit issue.
  4. Measure sensor signal voltage while engine runs and under boost demand
    Expected: Voltage increases consistent with boost pressure
    Interpretation: Low or no change indicates sensor or turbo pressure issue.
  5. Perform smoke or vacuum test for intake system leaks
    Expected: No detectable leaks
    Interpretation: Leaks can cause actual low boost readings resulting in code.

Repair Solutions

Replace boost pressure sensor "A" medium
Estimated Cost: $100 - $350

Sensor replacement often resolves low voltage circuit issues if wiring intact.

Repair or replace damaged wiring/connectors medium
Estimated Cost: $50 - $200

Critical to secure and route harness away from heat sources.

Fix vacuum/intake leaks medium
Estimated Cost: $50 - $300

Includes replacing hoses or gaskets causing intake pressure loss.

Inspect and repair turbocharger mechanical faults hard
Estimated Cost: $500 - $2000

Turbocharger issues may require professional service and significant cost.

PCM/ECM repair or replacement hard
Estimated Cost: $800 - $1500

Only after all sensor and wiring causes are ruled out; rare.

Common Misdiagnoses

Avoid these common diagnostic mistakes:

  • Interpreting vacuum or intake leaks as sensor failure without verifying actual sensor circuit voltage

Frequently Asked Questions

What does the P0237 code mean?

Turbocharger/Supercharger Boost Sensor "A" Circuit Low is the standard definition for P0237. This diagnostic code is triggered when the ECU detects a problem in the Air Intake.

Can P0237 cause engine damage?

This is a medium priority issue. Reduced engine power, possible limp-mode, decreased acceleration and fuel economy

Common signs of the P0237 error code

Drivers often report: Check engine light illuminated, Reduced engine power and acceleration, Poor fuel economy when this code is present.

What parts fail when P0237 is set?

The most common causes are: Faulty boost pressure sensor "A", Damaged or corroded wiring/connectors in sensor circuit, Vacuum leaks or intake pressure loss.

How much does it cost to fix P0237?

It depends on what needs to be fixed. Repair or replace damaged wiring/connectors repairs are cheaper (~$200), while Inspect and repair turbocharger mechanical faults repairs are on the higher end (~$2000).

Does P0237 affect Ford, Toyota, or Honda?

The P0237 code is a generic powertrain code, meaning it applies to almost all makes and models, such as Honda, Toyota, VW, Ford, and Chevy.

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