P2350 – Cylinder 15 Above Knock Threshold

System: Powertrain | Standard: ISO/SAE Controlled | Fault type: General | Location: Cylinder 15

Definition source: SAE J2012/J2012DA (industry standard)

P2350 indicates the powertrain control system has detected that combustion knock activity attributed to cylinder 15 has exceeded a calibrated threshold. This is not a direct confirmation of engine damage or a single failed part; it is a monitored condition based on sensor inputs and control-module logic. How the code sets, how quickly it returns, and what data is stored with it (freeze frame, misfire counters, knock learn values, or load conditions) can vary by vehicle. Always verify the exact enable criteria, related DTCs, and test specifications using the appropriate service information.

What Does P2350 Mean?

P2350 means Cylinder 15 Above Knock Threshold. In practical diagnostic terms, the control module has determined that knock intensity for cylinder 15 is higher than the allowed limit under the conditions when monitoring is active. The DTC structure itself is defined by SAE J2012, but the exact strategy used to attribute knock to a specific cylinder, the thresholds, and the corrective actions (such as ignition timing reduction or torque management) vary by vehicle. Treat P2350 as a detected knock-above-threshold condition that requires confirmation with scan data and testing.

Quick Reference

  • System: Powertrain
  • Official meaning: Cylinder 15 Above Knock Threshold
  • Standard: ISO/SAE controlled
  • Fault type: Range/Performance
  • Severity: MIL illumination is possible, and the control module may reduce performance to protect the engine if knock persists.

Symptoms

  • MIL: Check engine light illuminated, sometimes after a specific load or temperature condition.
  • Reduced power: Noticeable loss of torque due to spark retard or torque management responses.
  • Rattle/ping: Audible knocking or pinging during acceleration or high load (may be intermittent).
  • Roughness: Engine vibration or uneven operation, especially under load when knock control is active.
  • Hesitation: Flat spot or stumble on tip-in as timing is pulled back to control knock.
  • Poor economy: Increased fuel consumption from conservative ignition timing and altered fueling strategies.
  • Related codes: Additional DTCs may appear (for example misfire, fuel trim, or sensor plausibility), depending on vehicle logic.

Common Causes

  • Connector or terminal fault: Loose fit, fretting, corrosion, moisture intrusion, or pushed-out pins in the knock sensor, harness junctions, or control module connector affecting the cylinder-specific knock signal path (varies by vehicle).
  • Wiring damage: Chafed, pinched, melted, or cracked insulation leading to intermittent opens or shorts that distort the knock sensor signal reaching the control module.
  • Poor power/ground integrity: Weak sensor reference, poor ground, or shared ground issues introducing noise into the knock detection circuit and causing an apparent over-threshold condition.
  • Knock sensor issue: Sensor internal fault, degraded sensitivity, or mounting/torque problems (where applicable) that cause an inaccurate or noisy signal.
  • Mechanical engine knock/detonation conditions: Abnormal combustion or mechanical noise that drives actual knock intensity above the calibrated threshold; root cause varies by vehicle and operating conditions.
  • Ignition system problems: Misfire contributors such as weak spark output or incorrect ignition operation that can increase knock tendency under load.
  • Fuel delivery or mixture problems: Conditions that can promote knock (for example, mixture or delivery irregularities), depending on engine design and control strategy.
  • Airflow/boost control issues: Abnormal load calculation or boost control behavior (where equipped) that increases knock likelihood in certain operating regions.
  • Control module software/calibration concern: Strategy or calibration issues that misinterpret knock input or apply incorrect filtering; confirm only after circuit and mechanical checks.

Diagnosis Steps

Tools typically needed include a scan tool capable of reading freeze-frame and live data, a digital multimeter, and back-probing accessories. An oscilloscope or scan tool graphing function is helpful for spotting noise or dropouts on the knock signal. Basic hand tools for access and inspection are required, and service information is essential for pinouts, routing, and test procedures that vary by vehicle.

  1. Confirm the complaint and capture data: Verify P2350 is present. Record freeze-frame data, pending codes, and any companion powertrain codes (especially misfire, fuel control, or sensor reference/ground related codes) before clearing anything.
  2. Check for conditions that change diagnosis priority: Note any reduced-power operation, harsh mechanical noise, or abnormal idle. If severe noise is present, minimize run time and prioritize mechanical verification before extended testing.
  3. Clear and perform a controlled retest: Clear codes and perform a short road test or stationary run that recreates the original load/rpm conditions from freeze-frame (as safely possible). Confirm whether P2350 returns immediately, after a drive cycle, or intermittently.
  4. Visual inspection of the knock sensor circuit path: Inspect harness routing and connectors associated with knock sensing (varies by vehicle), looking for heat damage, rubbing, oil contamination, and poor connector seating. Correct obvious issues first and retest.
  5. Terminal and pin-fit checks: With the connector(s) disconnected and ignition off, inspect for corrosion, spread terminals, or backed-out pins. Perform a gentle pin-drag/pin-tension check where appropriate. Repair terminal issues and ensure proper connector locking.
  6. Wiggle test with live logging: With the scan tool graphing relevant knock-related PIDs (and misfire counters if available), manipulate the harness and connectors. Look for dropouts, sudden spikes, or correlation with movement. If the fault reacts, isolate the specific section and repair the wiring/connector.
  7. Power and ground voltage-drop testing: Under operating conditions specified by service information, perform voltage-drop tests across sensor grounds and related power/reference circuits feeding the sensing and processing path (varies by vehicle). Excessive drop indicates resistance in wiring, splices, or ground points that must be corrected.
  8. Circuit integrity checks (key off): Using service information pinouts, check continuity and isolation of the knock sensor signal circuit(s) between the sensor and control module. Identify opens, short-to-ground, or short-to-power conditions. Repair wiring faults and confirm repairs with a retest.
  9. Signal quality evaluation: If accessible and procedures allow, use a scope or scan tool graphing to evaluate the knock signal for noise, clipping, or intermittent loss during the conditions that set the code. Compare behavior across operating states (idle, light load, moderate load) to identify an abnormal pattern.
  10. Rule out contributors that can elevate knock: Verify basic engine operating integrity: check for misfire activity, abnormal fuel trims, and intake leaks as guided by service information. Address any confirmed related faults that can raise knock intensity, then repeat the drive cycle to see if P2350 returns.
  11. Evaluate sensor installation and mechanical noise sources: Where applicable, confirm the sensor is correctly mounted and secured per service procedures. If the engine exhibits verified mechanical knock, pursue mechanical diagnosis before replacing electronics.
  12. Consider control module strategy only after verification: If wiring, terminals, power/grounds, sensor function/installation, and mechanical contributors check out, follow service information for any module-side tests or software validation steps. Replace or reprogram only when the diagnostic path supports it.

Professional tip: Treat P2350 as an over-threshold detection, not an automatic parts verdict. The fastest path is to use freeze-frame to reproduce the exact operating window, then combine a wiggle test with live-data logging and voltage-drop testing to uncover intermittent resistance or noise sources that won’t show up in static continuity checks.

Need wiring diagrams and factory-style repair steps?

Powertrain faults often require exact wiring diagrams, connector pinouts, and guided test steps. A repair manual can help you confirm the cause before replacing parts.

Factory repair manual access for P2350

Check repair manual access

Possible Fixes & Repair Costs

Repair costs for P2350 vary widely by vehicle because the fix depends on what caused cylinder 15 to exceed the knock threshold, how accessible the components are, and whether wiring repairs or component replacement is required after confirming the fault with testing.

  • Correct fuel-related contributors (as verified): Drain/refill with the correct fuel grade if contamination or incorrect fuel is confirmed, and address the source of contamination.
  • Repair wiring or connectors: Fix damaged harness sections, corrosion, poor pin fit, or loose connections affecting the knock sensor circuit path used for cylinder identification (layout varies by vehicle).
  • Restore power/ground integrity: Clean and secure grounds, repair shared power feeds, and correct excessive resistance found during voltage-drop testing that can skew sensor signals.
  • Replace a faulty knock sensor (if proven): Replace the knock sensor only after tests show it is biased, unresponsive, or out of specification per service information.
  • Address ignition issues: Replace worn spark plugs, correct improper plug type/heat range, or repair ignition components when testing shows misfire/abnormal combustion contributing to knock.
  • Correct fueling/air faults: Repair intake leaks, injector issues, or abnormal fuel pressure only if live data and tests confirm lean operation or imbalance contributing to knock.
  • Verify cooling and combustion chamber conditions: Correct overheating causes, cooling fan operation, or airflow restrictions if elevated temperatures are verified to promote knock.
  • Software updates or relearns (where applicable): Perform control module updates, knock learn resets, or adaptive relearns only when service information indicates and the root cause is addressed.

Can I Still Drive With P2350?

Driving with P2350 may be possible for a short trip if the vehicle feels normal, but avoid heavy load, high RPM, and towing because continued knock can accelerate engine damage. If you notice reduced power, severe pinging/knocking sounds, overheating, flashing warning indicator, stalling, or any safety-related warnings, do not continue driving—shut down and diagnose or have the vehicle towed.

What Happens If You Ignore P2350?

Ignoring P2350 can allow persistent knock on cylinder 15, which may lead to protective torque reduction, worsening drivability, increased emissions, and potential long-term engine damage such as piston, ring, or bearing wear. If the underlying issue is electrical or sensor-related, the system may also make incorrect control decisions, compounding performance problems.

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

  • P2351 – Cylinder 16 Above Knock Threshold
  • P2349 – Cylinder 14 Above Knock Threshold
  • P2348 – Cylinder 13 Above Knock Threshold
  • P2347 – Cylinder 12 Above Knock Threshold
  • P2346 – Cylinder 11 Above Knock Threshold
  • P2345 – Cylinder 10 Above Knock Threshold

Key Takeaways

  • P2350 indicates knock severity: The control system detected cylinder 15 above the knock threshold; it does not prove a specific part has failed.
  • Vehicle designs vary: Cylinder identification and knock sensing strategy differ by vehicle, so confirm test procedures and pinouts with service information.
  • Start with verification: Check for related codes, freeze-frame data, and whether the condition is repeatable under similar load and temperature.
  • Protect the engine: Avoid high load until resolved; sustained knock can cause expensive mechanical damage.
  • Fix what you prove: Replace sensors or parts only after wiring, power/ground integrity, and contributing combustion causes are confirmed.

Vehicles Commonly Affected by P2350

  • Vehicles using cylinder-specific knock control: Platforms that calculate knock intensity per cylinder rather than only overall engine knock.
  • Engines with multiple knock sensors: Layouts where more than one sensor and harness branch are used to monitor different banks/regions.
  • High-compression or boosted applications: Engines operating closer to knock limits under load, where control sensitivity is higher (varies by calibration).
  • Heavy-duty powertrain configurations: Setups that routinely see high load and sustained torque demand.
  • Vehicles operating in hot climates: Higher intake and coolant temperatures can reduce knock margin if the system is already near threshold.
  • Vehicles with inconsistent fuel quality exposure: Operating environments where fuel octane or contamination issues are more likely.
  • High-mileage engines: Engines more prone to carbon buildup, cooling inefficiency, or ignition wear that can contribute to knock.
  • Vehicles with prior engine or harness repairs: Increased likelihood of connector issues, routing problems, or grounding faults after service work.

FAQ

Does P2350 mean the engine is physically damaged?

No. P2350 means cylinder 15 was detected above the knock threshold. That can be caused by true abnormal combustion, a sensor/signal issue, wiring problems, or control strategy limits. Mechanical damage is only confirmed through testing and inspection.

Can low-quality or incorrect fuel set P2350?

Yes, it can contribute if the fuel reduces knock resistance and the engine operates under conditions that promote knock. Confirm by reviewing operating conditions in freeze-frame data and verifying fuel quality/grade per service information before replacing parts.

Should I replace the knock sensor right away?

Not without proof. Knock sensors and their circuits should be tested first because wiring faults, poor grounds, engine noise sources, ignition problems, lean operation, or overheating can also cause the system to detect excessive knock on a specific cylinder.

Why would it show “cylinder 15” specifically?

Some engines and control strategies track knock by cylinder and can attribute knock intensity to a specific cylinder event. The exact method (sensor placement, signal processing, and cylinder mapping) varies by vehicle, so use service information to understand how cylinder 15 is determined.

What should I check first if P2350 returns after clearing?

Start by checking for related misfire, fuel trim, temperature, or knock sensor circuit codes; review freeze-frame data; inspect connectors and harness routing; and perform a road test while logging knock-related data under the conditions that originally set the code.

After completing repairs, clear the code, perform a verification drive cycle under similar load/temperature conditions, and confirm P2350 does not reset while monitoring knock-related live data and any related misfire or fuel-trim indicators.