P0237 – Boost sensor A circuit low

P0237 is an ISO/SAE controlled powertrain DTC that indicates the engine control module has detected a low electrical condition in the Boost sensor A circuit. In other words, the control module is seeing the Boost sensor A signal voltage lower than its acceptable threshold for the current operating conditions. Because the code is explicitly a circuit-low fault type, the diagnostic focus should stay on the sensor’s electrical circuit (reference voltage supply, sensor ground, signal wire integrity, connector condition, and terminal fit) before assuming a mechanical boost problem. When this fault is present, the control module may disregard the affected signal and apply protective strategies that can reduce engine output and alter driveability until the circuit problem is corrected.

P0237 Quick Answer

P0237 – Boost sensor A circuit low means the control module has detected that the Boost sensor A signal is electrically too low. Inspect the Boost sensor A connector and wiring first, then verify reference voltage, ground quality, and that the signal wire is not shorted to ground or open.

What Does P0237 Mean?

Official meaning: Boost sensor A circuit low. This DTC sets when the control module determines the Boost sensor A circuit voltage is below a calibrated minimum. The key point is that P0237 is reporting an electrical “low” condition in the circuit, not simply a confirmed low boost pressure condition.

The “A” designation is defined by the vehicle manufacturer’s sensor naming scheme. It identifies which boost-related pressure input the module is evaluating as “Boost sensor A.” To diagnose correctly, use service information for your exact application to confirm the sensor location and the correct circuit pins for reference voltage, ground, and signal.

Theory of Operation

A boost pressure sensor converts pressure into a voltage signal that the control module can interpret. Most designs use a regulated reference voltage (often 5 volts), a dedicated sensor ground, and a signal return line. The module continuously monitors the signal voltage and expects it to remain within a rational range for the current key state and engine operating conditions.

P0237 sets when the module detects the Boost sensor A signal is pulled low electrically—typically due to a short to ground, loss of reference voltage, excessive resistance in the signal path, or a poor ground that distorts the measured signal. Because this is a circuit-low fault type, a correct diagnosis verifies electrical integrity with measured values and load/voltage-drop testing, not guesses based on symptoms alone.

Symptoms

• Malfunction Indicator Lamp (Check Engine Light) illuminated
• Reduced engine power or reduced throttle response
• Limited boost command or protective torque reduction strategies
• Hesitation or sluggish acceleration, especially when load increases
• Driveability changes that may be more noticeable during acceleration or climbing grades
• Live data for Boost sensor A reading abnormally low or responding poorly to operating changes

Common Causes

• Boost sensor A signal circuit shorted to ground
• Open circuit or high resistance in the Boost sensor A signal wire
• Reference voltage supply to Boost sensor A missing or pulled low by another fault on the reference circuit
• High resistance or poor connection on the sensor ground circuit
• Connector problems at Boost sensor A (corrosion, moisture intrusion, backed-out terminals, poor terminal tension)
• Internal electrical failure of Boost sensor A causing consistently low output
• Harness damage (chafing, pinched wiring, heat damage) affecting reference, signal, or ground circuits
• Control module input or internal fault (rare, considered only after circuit verification)

Diagnosis Steps

Tools needed: Scan tool with freeze-frame and live data, DVOM (digital volt/ohm meter), appropriate wiring diagram/service information for the specific vehicle, and safe back-probing/terminal test tools. A fused jumper or other approved method to apply a light circuit load is helpful for finding high-resistance faults.

1. Confirm the code and capture data: Verify P0237 is present (stored/confirmed or pending). Record freeze-frame information and note any additional DTCs that may indicate reference voltage, sensor ground, or related circuit faults.
2. Verify the correct sensor: Using service information, identify which component is labeled “Boost sensor A” and confirm the connector pinout for reference voltage, ground, and signal.
3. Initial visual inspection: With ignition off, inspect the Boost sensor A connector, harness routing, and nearby wiring for chafing, pinching, heat damage, oil saturation, or contact with moving components. Repair obvious wiring damage before deeper testing.
4. Check for connector/terminal issues: Disconnect the sensor and inspect for corrosion, moisture, bent pins, spread terminals, or terminals pushed back in the connector body. Correct terminal fit issues and clean/dry as appropriate per service procedures.
5. Verify reference voltage: Key on, engine off. Measure the reference voltage at the Boost sensor A connector. If reference voltage is missing or low, follow the wiring diagram to determine whether the reference circuit is shared and isolate the cause (wiring fault or another component pulling the reference low).
6. Verify sensor ground integrity: Perform a voltage-drop test between the sensor ground terminal and battery negative while the circuit is powered (key on). Excessive voltage drop indicates resistance in the ground path that can contribute to a circuit-low condition.
7. Test the signal circuit for short to ground: With the sensor disconnected, test the signal circuit for unintended continuity to ground. Wiggle the harness during testing to help reveal intermittent shorts caused by chafing or a pinched loom.
8. Test the signal circuit for open/high resistance: Check continuity from the sensor connector signal pin to the control module pin (as specified in service information). If continuity exists, follow with an approved loaded test to detect high resistance that may not show up on a simple ohms check.
9. Evaluate scan data rationality: Observe Boost sensor A data PID with key on, engine off, and during controlled changes in operating conditions as appropriate. A signal that remains low despite verified reference and ground strongly supports a sensor or signal-path fault.
10. Clear, verify, and confirm the repair: After repairs, clear DTCs and confirm the code does not reset. Recheck live data and complete the applicable drive cycle/monitor conditions to ensure the circuit-low fault is resolved.

Professional tip: If P0237 resets immediately with key on, focus on hard electrical faults first—missing reference voltage, a signal short to ground, or a connector/terminal problem. Intermittent faults are best found by combining live data monitoring with harness movement and voltage-drop testing rather than relying only on static resistance checks.

Possible Fixes

• Repair wiring damage (short to ground, open circuit, or high resistance) in the Boost sensor A signal circuit
• Restore proper reference voltage supply to Boost sensor A (repair wiring or isolate a reference circuit issue per service information)
• Repair high resistance in the sensor ground circuit (splices, terminals, ground points) found through voltage-drop testing
• Clean, dry, and repair connector/terminal issues at Boost sensor A and related harness connectors
• Replace Boost sensor A only after confirming correct reference voltage and ground and verifying the signal remains abnormally low
• Repair/replace the control module only after all circuit tests confirm correct inputs reach the module and a module fault is proven

Can I Still Drive With P0237?

You may be able to drive with P0237, but you should expect reduced performance because the control module may limit output when it detects the Boost sensor A circuit low condition. Treat it as a drivability and safety concern if acceleration is significantly reduced, especially for merging or passing. If the vehicle exhibits severe hesitation, unstable running, or repeatedly enters a protective reduced-power mode, limit driving and diagnose the circuit fault promptly.

How Serious Is This Code?

P0237 can be serious primarily because it can cause the control module to restrict power and alter engine control strategies when it detects a circuit-low input. While the code is electrical in nature, the resulting reduced performance can create unsafe situations when predictable acceleration is needed. Additionally, leaving an electrical circuit fault unresolved can lead to intermittent behavior and repeated fault setting, making consistent engine control more difficult until the circuit low condition is corrected.

Common Misdiagnoses

The most frequent diagnostic error is treating P0237 as a mechanical “low boost” problem or replacing the sensor before verifying the electrical circuit. P0237 is specifically a circuit-low code, so skipping reference voltage checks, sensor ground voltage-drop testing, and signal-wire short-to-ground testing can lead to unnecessary parts replacement. Another mistake is relying only on continuity readings without load testing, which can miss high resistance caused by corrosion, damaged terminals, or partially broken wiring.

Most Likely Fix

The most likely fix is to correct an electrical fault that is pulling the Boost sensor A circuit low—such as repairing a short to ground, restoring a missing/low reference voltage supply, or fixing a poor ground or connector/terminal issue at the Boost sensor A circuit. Replace Boost sensor A only after the circuit is proven to provide correct reference voltage and ground and the signal remains low.

Repair Costs

Repair cost depends on whether the confirmed root cause is a sensor, wiring, connector issue, or control module problem. Verify the fault electrically before replacing parts.

Last updated: March 29, 2026