P0333 – Knock Sensor 2 Circuit High Bank 2

Last updated: April 4, 2026

P0333 means the engine computer sees an abnormally high signal on Knock Sensor 2 for Bank 2. Most drivers notice the check engine light first, and some feel reduced power because the computer may protect the engine by changing ignition timing. According to factory diagnostic data, this code indicates a “Knock Sensor 2 Circuit High Bank 2” condition, not a confirmed bad sensor. In plain terms, the PCM/ECM thinks the knock sensor circuit voltage stays higher than expected. That often points to wiring faults, connector issues, or a sensor circuit problem that needs testing.

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P0333 Quick Answer

P0333 points to a high-voltage condition in the Knock Sensor 2 circuit on Bank 2. Check the sensor connector and harness first, then verify the circuit voltage and ground integrity before replacing parts.

What Does P0333 Mean?

P0333 code meaning: “Knock Sensor 2 Circuit High Bank 2.” The PCM/ECM sets this code when it detects a higher-than-expected electrical signal from the Bank 2, Sensor 2 knock sensor circuit. In practice, the module may limit spark advance to prevent engine damage. That strategy can reduce power and fuel economy.

“Circuit High” describes what the module measures, not what the engine mechanically does. The PCM monitors the knock sensor signal line for plausibility. A high reading can come from an open in the signal return, a short to voltage, poor shielding, water intrusion in the connector, or internal sensor/circuit issues. You must confirm the circuit fault with electrical checks before you blame the sensor.

Theory of Operation

Knock sensors generate an AC signal when engine vibration matches knock frequencies. The PCM uses that signal to adjust ignition timing and protect the engine. Many systems bias the sensor circuit and filter noise inside the PCM. The module expects the signal to vary with engine conditions.

P0333 sets when the PCM sees the Knock Sensor 2 Bank 2 circuit stuck higher than its expected operating window. An open circuit can float the input high. A short to a voltage source can drive it high. Harness routing near ignition coils, alternator wiring, or damaged shielding can also push the input high.

Symptoms

P0333 symptoms often show up as a warning light and reduced performance, especially under load.

• Check engine light illuminated with P0333 stored as pending or confirmed
• Reduced power during acceleration due to spark timing changes
• Pinging concern reported by the driver, even if actual knock is not present
• Poor fuel economy from conservative ignition timing and altered torque strategy
• Hesitation on tip-in or climbing grades as the PCM limits advance
• Roughness under load that feels like misfire but does not set misfire codes
• Companion DTCs for knock sensor circuit, bank correlation, or sensor rationality on some platforms

Common Causes

• Open in the knock sensor 2 signal circuit (Bank 2): An open circuit leaves the input floating, so the PCM can interpret it as an abnormally high signal.
• Short to voltage on the knock sensor signal wire: Chafed insulation or a pinched harness can feed battery or reference voltage into the signal line and drive the reading high.
• Poor sensor ground path due to corrosion or high resistance: Added resistance in the ground return changes signal bias and can push the circuit toward a high reading.
• Connector problems at the knock sensor or intermediate junction: Spread terminals, moisture intrusion, or oil contamination can distort the signal and create a high-circuit fault.
• Incorrect knock sensor installed or wrong bank identification: A mismatched sensor design or wrong location can produce an abnormal output that the PCM flags as circuit high.
• Harness damage near hot or moving components: Heat-soak and vibration near exhaust manifolds or engine lifting points can break conductors internally and create false high signals.
• Sensor mounting or torque issue affecting sensor coupling: Improper mounting can alter the sensor’s output behavior and trigger a circuit high decision under certain conditions.
• PCM input circuit fault (less common): An internal bias or input conditioning problem can make the module read an artificially high knock sensor 2 signal.

Diagnosis Steps

Use a scan tool with freeze-frame access and live data, a DVOM with min/max, and back-probing tools. A lab scope helps confirm signal integrity on a knock sensor circuit. Get a wiring diagram that shows Bank 2 and knock sensor 2 routing. Plan for a careful harness inspection around hot exhaust areas and under-intake locations.

1. Confirm P0333 on the scan tool and note whether it shows as pending or confirmed/stored. Record freeze frame data, especially battery voltage, engine RPM, engine load, coolant temperature, and ignition state when the code set.
2. Review DTCs in all modules and look for related codes that change your path. Pay attention to other knock sensor codes, misfire codes, or power supply codes since they can influence knock control and testing conditions.
3. Inspect the power distribution basics before any PCM pin testing. Check the applicable fuses, fuse links, and engine grounds for looseness or corrosion, then verify charging system voltage stays stable during cranking and idle.
4. Verify PCM power and ground with voltage-drop testing under load. With the circuit operating, measure ground drop from the PCM ground pin to battery negative and keep it under 0.1V, because high resistance can skew sensor bias and signal interpretation.
5. Do a targeted visual inspection of the Bank 2 knock sensor 2 harness path before meter work. Look for melted loom, rub-through, oil saturation, or a harness trapped under an intake or bracket that could short the signal to voltage.
6. Disconnect the knock sensor 2 connector and inspect terminals closely. Check for green corrosion, coolant/oil intrusion, bent pins, and terminals that do not grip, since intermittent opens often present as a circuit high fault.
7. With key on and engine off, check the knock sensor signal circuit for a short to voltage. Back-probe the signal line at a safe access point and look for voltage where the wiring diagram indicates the circuit should not be driven high.
8. Check circuit integrity between the sensor connector and the PCM using the wiring diagram. Perform continuity checks with the harness flexed, but do not stop there, because continuity can pass while a loaded circuit fails.
9. Load-test the suspect circuits to find high resistance. Use a fused jumper or an appropriate test load and measure voltage drop across the signal return and ground path while loaded, since a weak connection often fails only under load.
10. If you have a scope, verify signal behavior while tapping near the sensor location and during a controlled RPM increase. Compare Bank 2 knock sensor 2 activity to the other knock sensor channel when the platform uses two sensors, because a flatlined or biased-high trace points to wiring or input bias issues.
11. Use a scan tool snapshot during a road test if the code sets intermittently. Freeze frame shows the conditions when P0333 set, while a snapshot captures live data at the moment the concern happens, which helps catch harness movement or heat-related faults.
12. After repairs, clear codes and verify P0333 does not return on a repeat drive under similar freeze-frame conditions. Confirm the appropriate OBD-II monitor completes and shows Ready/Complete, since clearing codes resets readiness to Not Ready.

Professional tip: Treat P0333 as a “circuit bias” problem first. An open or a short-to-voltage can read high without any real engine knock. Prove power, ground, and signal integrity with voltage-drop under load before you condemn the sensor or PCM.

Possible Fixes

• Repair an open or high-resistance section in the knock sensor 2 signal/ground circuit and verify with a loaded voltage-drop test.
• Repair a short to voltage on the knock sensor signal wire caused by chafing, melted insulation, or a pinched harness.
• Clean, dry, and re-pin or replace damaged knock sensor/engine harness connectors that show corrosion, poor tension, or fluid intrusion.
• Correct knock sensor 2 installation issues, including wrong part, wrong location, or improper mounting, after wiring integrity checks pass.
• Repair engine-to-chassis ground connections or power distribution faults that fail voltage-drop testing and affect sensor bias stability.
• Replace the PCM only after you verify the wiring, connector integrity, and signal behavior at the PCM pin, and you rule out external causes.

Can I Still Drive With P0333?

You can usually drive with a P0333 code, but you should treat it as a “limited power” risk. When the PCM sees Knock Sensor 2 Circuit High (Bank 2), it may assume it cannot trust knock feedback on that bank. Many strategies pull ignition timing as protection. That can reduce power and fuel economy. Avoid heavy throttle, towing, and long hill climbs until you diagnose it. If you hear pinging, rattling under load, or the engine feels hot, stop driving and repair it. True detonation can damage pistons and catalysts fast. If the vehicle enters reduced-power mode or misfires, drive it only to a shop.

How Serious Is This Code?

P0333 ranges from an inconvenience to a real durability concern, depending on what the engine is doing. If the engine runs smooth and you only have a MIL, the fault often points to a circuit issue like an open, poor connector contact, or harness damage that skews the signal high. In that case, you may mainly notice sluggish acceleration. If the engine pings under load, runs hotter than normal, or you see misfire and fuel trim codes with P0333, the risk goes up. Knock control protects the engine. Losing accurate input can lead to over-retarded timing, high exhaust temperature, and catalyst damage.

Common Misdiagnoses

Technicians often replace Knock Sensor 2 immediately because the code “names” it. That wastes money when the real issue sits in the connector, harness routing, or a poor ground path that biases the signal high. Another common mistake involves mixing up bank and sensor numbering. On many engines, Bank 2 sits opposite Bank 1, but layouts vary by model. I also see missed coolant or oil intrusion in the knock sensor valley area. That contamination can change signal behavior and create a high-input condition. Finally, some techs ignore freeze-frame data and miss that the code sets during cranking, pointing to wiring movement, starter current noise, or a disturbed ground.

Most Likely Fix

The most common repair direction for P0333 involves circuit verification and wiring repair, not immediate sensor replacement. Start with a close inspection of the Knock Sensor 2 (Bank 2) connector for spread terminals, moisture, and corrosion. Then load-test the harness and check for short-to-voltage or an open signal return, especially where the loom rubs on the intake, cylinder head, or firewall. If the circuit tests good end-to-end and the signal still reads high on live data, replace the knock sensor only after you confirm correct torque and clean mounting. After repairs, road-test under the monitor enable conditions listed in service information to confirm the code stays cleared.

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.