P2372 – Knock Sensor 1 Circuit Low (Bank 1)

System: Powertrain | Standard: ISO/SAE Controlled | Fault type: Circuit Low | Location: Bank 1, Sensor 1

Definition source: SAE J2012/J2012DA (industry standard)

P2372 indicates the powertrain control module has detected a low electrical signal condition in the Knock Sensor 1 circuit on Bank 1. In practical terms, the sensor signal is being pulled lower than expected for the current operating conditions, which points to an electrical issue rather than a confirmed mechanical engine problem. Because wiring layouts, sensor locations, and diagnostic enable criteria vary by vehicle, the exact test procedure and pin assignments must be verified in the correct service information. Treat this code as a circuit-low fault until testing proves otherwise.

What Does P2372 Mean?

P2372 – Knock Sensor 1 Circuit Low (Bank 1) means the control module has identified a “circuit low” condition on the Knock Sensor 1 signal path for Bank 1. Under SAE J2012 DTC conventions, the code format identifies the affected system and the specific fault entry, while the official definition provides the authoritative meaning: the knock sensor circuit input is lower than the module expects when the monitor runs. This typically indicates an electrical short to ground, loss of power/feed, excessive resistance causing signal drop, or a sensor/circuit fault that pulls the signal low.

Quick Reference

• System: Powertrain
• Official meaning: Knock Sensor 1 Circuit Low (Bank 1)
• Standard: ISO/SAE controlled
• Fault type: Circuit Low
• Severity: The MIL may illuminate and the engine may reduce performance or fuel economy because knock control strategy can be limited when the signal is unreliable.

Symptoms

• MIL/Check engine light: Lamp on or pending code stored after the monitor runs.
• Reduced power: Noticeable loss of acceleration if spark timing is adjusted to protect the engine.
• Poor fuel economy: Increased consumption due to conservative ignition timing or altered load strategy.
• Roughness: Light hesitation, stumble, or unevenness under load depending on timing response.
• Pinging/knock perception: Audible knock may be noticed, or perceived knock control may feel inconsistent (not proof of actual detonation).
• Intermittent behavior: Symptoms may come and go with vibration, heat, or harness movement.
• Failed emissions readiness: Readiness monitors may not set or may fail if the fault returns during testing.

Common Causes

• Harness short-to-ground: The knock sensor signal circuit rubbed through and contacting engine ground or another grounded conductor, pulling the signal low.
• Connector damage: Bent pins, corrosion, moisture intrusion, poor pin fit, or a partially seated connector at the knock sensor or control module creating a low-signal condition.
• High resistance on power/feed (if equipped): Some designs use a sensor feed/reference; excessive resistance in that feed can collapse the circuit and present as a low input (varies by vehicle).
• Ground circuit issue (if equipped): A compromised sensor ground path can alter circuit biasing and result in a consistently low reading (varies by vehicle).
• Signal wire short to a low-voltage circuit: Chafing or harness routing allows the knock sensor line to couple/short into another low-side controlled circuit.
• Sensor internal fault: Knock Sensor 1 has an internal short or failure that forces the output low even when the wiring is intact.
• Incorrect connector/harness repair: Wrong terminal type, poor crimp, excessive solder wicking, or damaged insulation causing resistance and unintended grounding.
• Control module pin/terminal problem: Spread terminals, fretting, or water intrusion at the module connector causing the input to be pulled low.

Diagnosis Steps

Tools typically needed include a scan tool with live data and freeze-frame access, a digital multimeter, and back-probing or pin-probe tools. A wiring diagram and connector views from service information are important because circuit layout varies by vehicle. If available, use a breakout lead or test harness to avoid damaging terminals, and plan for a road test to log data under load.

1. Confirm the code and capture context: Verify P2372 is present. Record freeze-frame data (load, RPM, coolant temperature) and note any companion powertrain codes that could affect engine operation or sensor reference circuits.
2. Check for obvious wiring/connector faults first: With ignition off, inspect the Knock Sensor 1 connector and nearby harness routing for oil saturation, abrasion, pin damage, or contact with hot/sharp engine components. Correct any visible issues before deeper testing.
3. Clear and perform a short verification drive: Clear DTCs and run the engine through the conditions shown in freeze-frame (as safely possible). If P2372 resets quickly, treat it as a hard fault and proceed with circuit testing.
4. Use live data to confirm “low” behavior: Monitor knock sensor-related parameters available on the scan tool (naming varies by vehicle). Look for a signal that is stuck low, flatlined, or not responsive to changes in engine load. Save a short data log for comparison after repairs.
5. Wiggle test while monitoring live data: With the engine idling, gently manipulate the harness and connector at the sensor and along the harness path. If the signal changes or the code sets intermittently, suspect poor pin fit, broken strands near the connector, or harness chafing.
6. Check for a short-to-ground on the signal circuit: Key off, disconnect the knock sensor and the relevant control module connector (per service guidance). Test the signal wire for continuity to ground. Any unintended continuity indicates a short-to-ground or contamination path that can force a circuit low.
7. Verify circuit integrity end-to-end: With both ends still disconnected, check continuity of the signal circuit from the sensor connector to the control module pin. Also check for short-to-other-circuits by testing between the signal wire and adjacent wires in the connector/harness.
8. Inspect terminals closely and correct fit: Examine terminals for corrosion, backed-out pins, spread female terminals, or fretting. Repair/replace terminals as needed and ensure connectors lock fully. Many “circuit low” faults are terminal-contact problems rather than the sensor itself.
9. Perform voltage-drop testing where applicable: If the vehicle uses a sensor feed/reference and/or dedicated ground (varies by vehicle), test those circuits under operating conditions using voltage-drop methods rather than only static resistance checks. Excessive drop indicates high resistance that can pull the circuit low.
10. Sensor check after wiring is proven: If wiring, terminals, feed/ground (if used), and shorts are ruled out, replace Knock Sensor 1 only after confirming it is the remaining likely cause. After replacement, clear codes and repeat the same drive conditions while logging data to confirm the low-signal condition is resolved.
11. Final verification: Recheck for pending codes, confirm readiness/monitors as applicable, and ensure the harness is secured away from heat and abrasion points to prevent repeat failures.

Professional tip: When chasing a “circuit low” code, prioritize locating an unwanted path to ground or a high-resistance connection that collapses the circuit under vibration and heat. Compare your live-data log before and after each change, and avoid condemning the sensor until the harness/terminal checks and short-to-ground tests are conclusive.

Possible Fixes & Repair Costs

Repair costs for P2372 vary widely because the same “circuit low” condition can be caused by wiring, connector issues, grounding problems, or a component fault. Total cost depends on the diagnostic time required, parts replaced, and labor access, which varies by vehicle.

• Repair damaged wiring: Locate and repair shorts-to-ground, chafed insulation, pinched harness sections, or melted wiring affecting the knock sensor 1 signal circuit (Bank 1).
• Restore connector integrity: Clean corrosion, correct poor terminal fit, replace damaged connector housings, and ensure proper pin tension at the sensor and control module connectors.
• Correct power/ground path issues: Repair shared ground points, loose fasteners, or high-resistance ground paths that can pull the signal low; confirm with voltage-drop testing under load.
• Replace knock sensor 1: If circuit checks pass but the sensor output remains electrically low per service information tests, replace the sensor and verify proper installation and routing.
• Address harness routing and shielding: Re-route or re-secure the harness to prevent contact with hot/moving parts and restore any missing shielding/retainers that can lead to repeated circuit damage.
• Control module circuit repair: If verified by pinpoint tests, repair the signal input circuit at the control module connector (terminal damage) or replace the module only after all external circuit faults are ruled out.

Can I Still Drive With P2372?

You can sometimes drive with P2372, but it’s best to minimize driving until the circuit-low condition is diagnosed because knock sensing may be unreliable and the control system may alter engine operation. If you notice severe power loss, rough running, stalling, or any warning messages indicating reduced power, avoid driving and arrange service to prevent further issues.

What Happens If You Ignore P2372?

Ignoring P2372 can lead to continued warning light illumination and persistent drivability concerns depending on vehicle strategy. Because the issue is an electrical “circuit low” condition, it may worsen as wiring/connector damage progresses, potentially causing intermittent faults, reduced performance, and difficulty passing emissions inspection where OBD readiness and fault status are checked.

Last updated: February 15, 2026

Vehicles Commonly Affected by P2372

• Vehicles with knock sensor-equipped engines: Any platform using knock sensor feedback for engine protection and timing control may set this code.
• High-mileage vehicles: Harness insulation wear, heat cycling, and connector aging can increase the likelihood of circuit-low conditions.
• Vehicles exposed to moisture/corrosion: Road salt, humidity, or water intrusion can degrade terminals and create low-signal paths.
• Vehicles with recent engine work: Disturbed harness routing, pinched wiring, or partially seated connectors can trigger a circuit-low fault after repairs.
• Vehicles with tight engine-bay packaging: Harnesses routed near brackets, edges, or hot components are more prone to chafing and shorts-to-ground.
• Vehicles operated in extreme heat: Elevated temperatures can harden insulation and weaken connector seals, increasing circuit faults over time.
• Vehicles with rodent damage history: Chewed wiring can create intermittent or hard shorts pulling the signal low.

For best results, confirm the circuit-low condition with scan data, inspect connectors and harness routing carefully, and only replace parts after tests identify the exact source of the low signal.