P2373 – Knock Sensor 1 Circuit High (Bank 1)

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

Definition source: SAE J2012/J2012DA (industry standard)

P2373 indicates the powertrain control module detected a “circuit high” condition on Knock Sensor 1 for Bank 1. In practical terms, the sensor signal or its circuit is being seen as higher than expected due to an electrical issue such as an open in the return path, a short to power, an abnormal reference condition, or a connector/wiring fault. This code describes an electrical signal condition, not a confirmed mechanical engine knock problem by itself. DTC behavior, sensor location, wiring design, and enabling criteria vary by vehicle, so confirm the exact circuit description and test specifications in the correct service information.

What Does P2373 Mean?

P2373 – Knock Sensor 1 Circuit High (Bank 1) means the control module has determined the Knock Sensor 1 signal circuit on Bank 1 is reading abnormally high. Under SAE J2012 conventions, the DTC structure identifies the system and the specific fault entry; for this code, the key qualifier is “Circuit High,” which points to an electrical high-input condition in the knock sensor circuit (such as a short to a power source, an open ground/return, an open signal causing a biased-high reading, or a connector/pin issue). The DTC does not, by itself, prove the sensor is bad.

Quick Reference

• System: Powertrain
• Official meaning: Knock Sensor 1 Circuit High (Bank 1)
• Standard: ISO/SAE controlled
• Fault type: Circuit High
• Severity: MIL illumination is possible, and engine control may be affected, potentially reducing performance or altering timing strategies depending on vehicle logic.

Symptoms

• MIL/Check engine: Warning lamp illuminated with P2373 stored (sometimes pending at first).
• Reduced performance: Noticeable loss of power if the control module switches to a protective strategy.
• Hesitation: Tip-in stumble or sluggish response, especially under load.
• Poor fuel economy: Increased fuel consumption if timing and combustion control are adjusted.
• Rough running: Intermittent roughness if the fault is connection-related and comes and goes.
• Driveability inconsistency: Symptoms may vary with vibration, engine movement, or temperature if wiring/connector integrity is marginal.
• Additional codes: Related sensor circuit or reference/ground codes may appear depending on how the circuit is shared.

Common Causes

• Harness short-to-power: Knock sensor signal circuit contacting a power feed, pushing the signal high.
• Open ground or poor ground path: Missing sensor ground (or shared ground issue) causing the circuit to bias high.
• Signal circuit open: Broken conductor, poor terminal tension, or intermittent open that makes the input float high.
• Connector faults: Corrosion, moisture intrusion, oil saturation, bent pins, or partially seated connectors at the sensor or engine harness.
• Improper routing: Harness routed near high-current wiring/ignition components, increasing susceptibility to induced electrical noise that can appear as a high signal.
• Sensor internal fault: Knock Sensor 1 internal failure producing an abnormally high output or leakage to its supply/ground path (varies by vehicle design).
• PCM/ECM input circuit issue: Damaged control module input stage or reference bias circuit causing a persistently high reading.
• Aftermarket electrical additions: Non-factory splices, tapped power sources, or poor repairs near the knock sensor circuit creating unintended voltage feed.

Diagnosis Steps

Tools typically needed include a scan tool with live-data logging, a digital multimeter, and back-probing leads. Access to vehicle-specific wiring diagrams and connector pinouts is essential because knock sensor circuits vary by vehicle. If available, an oscilloscope can help identify a biased-high or noisy signal. Basic hand tools for connector inspection, cleaning supplies, and materials for wiring repair are also helpful.

1. Confirm the DTC and context: Scan for P2373 and record freeze-frame data, pending codes, and any related powertrain codes. Clear codes and see if P2373 resets immediately or only under specific operating conditions.
2. Verify live-data behavior: With the scan tool, monitor the knock sensor-related PID(s) that apply (naming varies by vehicle). Look for a signal that appears stuck high, implausibly high, or that does not respond in a reasonable way to changes in engine operating conditions.
3. Perform a focused visual inspection: Inspect Knock Sensor 1 connector and the engine harness in the area for chafing, pinched wiring, contact with hot/exhaust components, or recent repair work. Pay close attention to spots where the harness could rub against brackets or the engine block.
4. Check connector fit and terminal condition: Key off, disconnect the sensor connector and inspect for corrosion, moisture, oil contamination, bent pins, spread terminals, or poor pin retention. Correct any seating issues and ensure connectors lock fully when reinstalled.
5. Wiggle test while logging: Reconnect as needed and, with the engine running or key on as applicable, gently wiggle the harness and connector while logging knock sensor PIDs and monitoring for abrupt changes or dropouts. If P2373 sets during movement, suspect an intermittent open, poor terminal tension, or a short-to-power that appears under vibration.
6. Check for short-to-power on the signal circuit: With the circuit isolated per service information (sensor and/or module side unplugged as required), use the multimeter to test the knock sensor signal wire for unintended voltage presence. If voltage is present when it should not be, trace for a short to a power feed or an incorrect splice.
7. Check for opens and high-resistance paths: Using wiring diagrams, test continuity end-to-end on the signal path (and any dedicated ground/return if used) and verify there is no open circuit. If continuity is intermittent, flex the harness during testing to locate the fault.
8. Perform voltage-drop testing on grounds: With the circuit powered in its normal operating state (varies by vehicle), perform voltage-drop tests on the relevant engine/sensor ground paths rather than relying only on static resistance checks. Excessive voltage drop indicates a ground path problem that can bias the circuit high.
9. Evaluate shielding/routing issues: If the wiring uses shielding, inspect shield integrity and grounding method per service information. Verify the harness is not routed alongside high-current wiring or ignition components; reroute or secure as required to reduce induced noise that could be interpreted as a high input.
10. Sensor substitution only after circuit checks: If power/ground integrity and wiring tests pass, suspect Knock Sensor 1. Replace the sensor only after confirming the circuit is not being driven high by a wiring fault, then clear codes and road test while logging to confirm the fault does not return.
11. Consider control module input fault last: If the sensor and wiring are verified good and P2373 persists, follow service information for module-side pinpoint tests. Confirm connector pin fit at the module and rule out harness issues before considering module repair/replacement.

Professional tip: Treat “circuit high” as an electrical diagnosis first: prove whether the signal is being driven high by a short-to-power, biased high by an open ground/open circuit, or falsely elevated by routing/noise. Document results from each isolation step (sensor unplugged, harness isolated, module connector checks) so you can identify exactly where the high condition is introduced.

Possible Fixes & Repair Costs

Repair costs for P2373 vary widely because the root cause can be as simple as a connector issue or as involved as harness repair. Final cost depends on verified diagnosis results, parts replaced, labor time, and access to the sensor and related wiring (varies by vehicle).

• Repair connector issues: Clean corrosion, correct terminal tension, and fully seat/lock the knock sensor 1 connector and any intermediate connectors in the circuit.
• Harness repair: Repair or replace damaged wiring where the signal is shorted to power, insulation is rubbed through, or the circuit is intermittently open and floating high.
• Restore ground/reference integrity: Repair poor grounds, broken ground splices, or shared reference circuits that can bias the knock sensor signal high.
• Replace knock sensor 1: Replace the sensor only after confirming the circuit and connectors are sound and the sensor itself is the source of the high signal condition.
• ECM/PCM connector service: Address bent pins, poor pin fit, moisture intrusion, or backed-out terminals at the control module connector that can elevate the sensed signal.
• Module replacement/programming: Replace and program the ECM/PCM only if all circuit checks pass and service information supports module fault as a confirmed cause.

Can I Still Drive With P2373?

You can often drive short distances with P2373, but it is best treated as a priority electrical fault because an incorrect knock sensor signal can affect ignition timing strategy and drivability. If you notice reduced power, heavy knocking/pinging, severe hesitation, misfire, overheating, or any warning that affects braking/steering, do not continue driving—stop and diagnose the circuit high condition first.

What Happens If You Ignore P2373?

Ignoring P2373 can lead to ongoing MIL illumination and prolonged operation with inaccurate knock input, which may cause reduced performance, poor fuel economy, and inconsistent throttle response. If the circuit fault worsens (intermittent wiring or connector failure), drivability complaints may become more frequent and harder to pinpoint, and additional fault codes may set.

Last updated: February 15, 2026

Vehicles Commonly Affected by P2373

• Vehicles with piezoelectric knock sensors: Common on many gasoline engines using knock-based timing control.
• Engines with banked cylinder layouts: V-type and other multi-bank configurations where “Bank 1” identification is required.
• High-heat engine bays: Platforms where harnesses run near exhaust components and insulation can degrade.
• Vehicles with under-intake harness routing: Designs where the knock sensor wiring is buried and subject to pinching during service.
• Higher-vibration powertrains: Applications where connector fretting and terminal micro-movement can occur.
• Vehicles with prior engine or harness work: Repairs that may leave connectors partially latched or wiring improperly secured.
• Vehicles exposed to water or corrosion: Environments that promote connector contamination and increased likelihood of biased signals.
• Older platforms: Age-related brittleness and loom damage can increase electrical fault frequency.

Always verify bank identification, connector pinout, and test procedures in the correct service information for your vehicle to avoid misdiagnosis and unnecessary parts replacement.