P2377 – Knock Sensor 2 Circuit High (Bank 2)

System: Powertrain | Standard: ISO/SAE Controlled | Fault type: Circuit High | Location: Bank 2, Sensor 2

Definition source: SAE J2012/J2012DA (industry standard)

P2377 indicates the powertrain control module detected a high electrical input in the Knock Sensor 2 signal circuit on Bank 2. “Circuit High” points to an electrical condition (such as an unintended voltage present on the signal line, an open ground/return, or a short to power) rather than confirming a mechanical knock problem by itself. Symptoms and test methods can vary by vehicle, so use the correct service information and wiring diagrams for your exact application. Diagnose it as a circuit-high fault first before replacing parts.

What Does P2377 Mean?

P2377 – Knock Sensor 2 Circuit High (Bank 2) means the engine management system has determined the Knock Sensor 2 circuit on Bank 2 is reporting a higher-than-expected electrical signal. Under SAE J2012 DTC structure, the code identifies the affected system and the specific fault entry, while the “Circuit High” wording indicates the failure mode: an abnormally high input condition in the circuit. Because this is a signal-level fault, the correct approach is to verify wiring integrity, connector condition, proper power/ground references, and sensor/circuit behavior under operating conditions per service information.

Quick Reference

  • System: Powertrain
  • Official meaning: Knock Sensor 2 Circuit High (Bank 2)
  • Standard: ISO/SAE controlled
  • Fault type: Circuit High
  • Severity: The MIL may illuminate and the control module may reduce ignition advance to protect the engine, which can affect performance and fuel economy.

Symptoms

  • MIL on: Check engine light illuminated with P2377 stored as current or history.
  • Reduced performance: Noticeable loss of power due to protective ignition/timing strategy.
  • Poor fuel economy: Increased consumption if timing is pulled back as a precaution.
  • Rough running: Hesitation or uneven acceleration, especially under load.
  • Knock control behavior: Live data may show abnormal knock sensor activity or timing corrections that do not match operating conditions.
  • Intermittent symptoms: Issue may appear or disappear with vibration, heat, or moisture affecting a high-input circuit condition.

Common Causes

  • Connector fault: Loose, corroded, oil-contaminated, or water-intruded connector at Knock Sensor 2 (Bank 2) causing an unintended high signal.
  • Signal circuit short-to-power: Chafed harness contacting a voltage feed or another powered circuit, driving the knock sensor signal high.
  • Open ground/return path: Broken ground wire, poor splice, or high resistance in the sensor return leading the module to interpret an abnormally high input.
  • Harness damage: Pinched, stretched, or rubbed-through wiring between the sensor and the control module creating intermittent or constant high input.
  • Poor terminal fit: Spread pins, backed-out terminals, or weak pin tension causing unstable contact that can bias the circuit high.
  • Incorrect routing or shielding issue: Wiring routed near high-current components or compromised shielding (varies by vehicle) that can distort the signal toward a high reading.
  • Sensor internal fault: Knock Sensor 2 (Bank 2) internal failure that results in a persistently high output or abnormal biasing of the circuit.
  • Control module circuit issue: Internal fault in the receiving input circuit (rare) or connector damage at the module that makes the input read high.

Diagnosis Steps

Tools typically needed include a scan tool with live-data logging, a digital multimeter, and access to vehicle-specific wiring diagrams and connector views. Depending on vehicle design, a lab scope may help validate signal behavior. Basic hand tools for connector inspection and harness access are also useful. Always follow service information for connector handling and any required relearn or confirmation drive.

  1. Confirm the code and freeze-frame context: Verify P2377 is present and record freeze-frame data and any accompanying DTCs. Address related power, ground, or reference-circuit codes first, since they can force a high-input reading.
  2. Verify correct bank and sensor identification: Using service information, confirm which side is Bank 2 and which component is Knock Sensor 2 on that bank. Misidentification can lead to testing the wrong connector or harness branch.
  3. Perform a targeted visual inspection: Inspect the sensor connector, harness routing, and nearby brackets or heat sources. Look for rubbed insulation, crushed sections, prior repair points, oil saturation, or evidence of moisture intrusion.
  4. Check connector integrity: With the key off, disconnect the sensor connector and inspect terminals for corrosion, bent pins, backed-out terminals, and pin-fit issues. Repair terminal tension or replace damaged terminals as needed, then ensure connectors seat and lock properly.
  5. Wiggle test while monitoring live data: Reconnect as required and monitor the knock sensor input/related PID(s) on the scan tool (names vary by vehicle). Wiggle the harness at the sensor, along the routing, and at the control module connector area. If the reading spikes high or the fault toggles, focus on that section.
  6. Check for short-to-power on the signal circuit: Using the wiring diagram, identify the signal circuit and test for unintended continuity to known power feeds with the connector(s) unplugged. If continuity appears where it should not, isolate by separating harness branches and inspecting for chafing points.
  7. Verify power/ground integrity with voltage-drop testing: If the circuit uses a dedicated ground/return or shared sensor ground (varies by vehicle), perform voltage-drop tests on the ground/return path under the conditions specified in service information. Excessive drop indicates resistance in wiring, splices, or connections that can bias the input high.
  8. Check circuit continuity end-to-end: With relevant connectors unplugged, verify continuity from the sensor connector to the control module connector for each involved circuit. Also check for unintended continuity between adjacent circuits (shorts) that could pull the input high.
  9. Evaluate sensor behavior: If wiring and connectors test good, evaluate Knock Sensor 2 (Bank 2) per service information. On some vehicles this includes comparing signal activity between banks, performing a tap/response check, or validating with a lab scope to see if the signal is biased high.
  10. Inspect the control module connector and input pin: Check for corrosion, water tracks, pin damage, or poor pin fit at the module connector associated with the knock sensor input. If wiring is proven good and the signal remains high at the module input, follow service information for module input-circuit diagnostics (module failure is uncommon).
  11. Clear codes and run a confirmation check: After repairs, clear DTCs and perform the specified drive cycle or enabling conditions (varies by vehicle). Re-scan for P2377 and confirm the live data remains stable without high-input events.

Professional tip: When the issue is intermittent, prioritize capturing a live-data log during a wiggle test and during the exact operating conditions shown in freeze-frame (load, RPM, temperature). A high-input DTC is often caused by a harness/terminal problem that only presents with vibration, heat soak, or movement; logging helps you prove the moment the circuit goes high and pinpoint the affected harness section.

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Factory repair manual access for P2377

Check repair manual access

Possible Fixes & Repair Costs

Repair cost for P2377 varies widely because the same “circuit high” condition can be caused by wiring, connector issues, sensor faults, or control-module input problems. Total cost depends on verified root cause, access time, required parts, and labor rates.

  • Repair wiring harness damage by fixing chafed insulation, pinched sections, or heat-damaged wiring that could short the signal to a power source.
  • Clean and secure connectors by removing corrosion/contamination, correcting poor pin fit, and ensuring proper terminal tension and locking.
  • Restore proper ground integrity by repairing open grounds, high-resistance ground paths, or ground splice issues affecting the knock sensor circuit.
  • Replace Knock Sensor 2 (Bank 2) only after confirming the sensor is the source of the high-input condition and the circuit tests good end-to-end.
  • Repair reference/supply circuit faults if the circuit is being pulled high by an unintended feed or shared-circuit problem (varies by vehicle).
  • Address control module connector issues by verifying terminal condition at the module, repairing bent pins, water intrusion, or backed-out terminals.
  • Reflash/reprogram if required by service information only when diagnostics indicate a calibration-related issue and no wiring/sensor faults remain.

Can I Still Drive With P2377?

You may be able to drive short distances if the vehicle feels normal, but P2377 indicates an electrical high input on Knock Sensor 2 (Bank 2), which can affect how the powertrain manages ignition timing and engine protection. If you notice reduced power, severe hesitation, abnormal engine noise, overheating indications, or the vehicle enters a fail-safe mode, avoid driving and diagnose promptly. If the vehicle has stalling, no-start, or any warning that affects steering or braking, do not drive.

What Happens If You Ignore P2377?

Ignoring P2377 can lead to ongoing MIL illumination, repeated fail-safe responses, and inconsistent engine performance because the knock input may be interpreted incorrectly or deemed unreliable. Over time, continued operation with a knock-sensor circuit high condition can contribute to poor drivability, increased fuel consumption, and potential catalyst stress if combustion control is adversely affected, depending on vehicle strategy.

Compare nearby knock trouble codes with similar definitions, fault patterns, and diagnostic paths.

  • P2373 – Knock Sensor 1 Circuit High (Bank 1)
  • P2354 – Cylinder 3 Knock Sensor Circuit
  • P2353 – Cylinder 2 Knock Sensor Circuit
  • P2352 – Cylinder 1 Knock Sensor Circuit
  • P2351 – Cylinder 16 Above Knock Threshold
  • P2350 – Cylinder 15 Above Knock Threshold

Key Takeaways

  • P2377 is an electrical fault: it indicates Knock Sensor 2 Circuit High (Bank 2), not a confirmed mechanical problem by itself.
  • Wiring and connectors are prime suspects: shorts-to-power, open grounds, corrosion, and pin-fit issues commonly create high-input signals.
  • Verify with testing: confirm the high condition with circuit checks and live-data behavior before replacing parts.
  • Driveability impact varies: some vehicles may reduce performance or alter timing strategies when knock input is unreliable.
  • Fix the root cause only: replace the sensor or control components only after proving the circuit is intact and the component is at fault.

Vehicles Commonly Affected by P2377

  • V-type engines where Bank 2 is clearly defined and uses a dedicated knock sensor circuit for that bank.
  • Engines with multiple knock sensors that label sensors by number (Sensor 1 vs Sensor 2) and monitor separate inputs.
  • Vehicles with tight underhood packaging where harness routing near hot components increases the chance of insulation damage.
  • High-mileage vehicles with aging connectors, brittle wiring insulation, or prior repairs affecting terminal fit.
  • Vehicles exposed to moisture or road salts that can accelerate connector corrosion and increase circuit faults.
  • Vehicles with recent engine service where connectors may be left loose, pins may be stressed, or harnesses may be misrouted.
  • Vehicles with aftermarket electrical modifications that can introduce shared-power faults or harness interference (varies by vehicle).
  • Vehicles with prior collision or rodent damage affecting engine harness integrity and causing unintended shorts.

FAQ

Does P2377 mean Knock Sensor 2 is bad?

No. P2377 means the Knock Sensor 2 circuit on Bank 2 is reading “high,” which is an electrical signal condition. A failed sensor is possible, but wiring shorts-to-power, open grounds, connector corrosion, or terminal fit issues must be ruled out with testing first.

What does “circuit high” indicate for this code?

“Circuit high” indicates the control module is seeing a higher-than-expected voltage/signal on the Knock Sensor 2 (Bank 2) input. This commonly points to a short-to-power, an open or weak ground path, or a wiring/connector issue that causes the input to be pulled high.

Can a loose connector trigger P2377?

Yes. A loose, corroded, or poorly pinned connector can create an open circuit or unstable connection that results in a high-input reading at the module. Inspect for backed-out terminals, damaged seals, contamination, and poor terminal tension, then verify with a wiggle test while monitoring live data.

Will P2377 clear by itself?

It may clear temporarily if the condition is intermittent, but it will typically return if the underlying electrical fault remains. Even if the MIL turns off, the fault may be stored as history and can reappear under similar conditions such as vibration, heat soak, or moisture exposure.

Should I replace the control module for P2377?

Not as a first step. Module replacement is rarely the correct first repair for a circuit high code and should only be considered after confirming wiring integrity, connector condition, power/ground quality, and sensor behavior, and after following the vehicle’s service information for any additional pinpoint tests.

After repairs, confirm the fix by clearing stored faults, performing a complete drive cycle as outlined in service information, and verifying that Knock Sensor 2 (Bank 2) input and related monitors behave normally without the code returning.