Fix P0330: Mechanic’s solutions that WORKED

The code P0330: Knock Sensor 2 Circuit Malfunction (Bank 2) indicates a fault in the knock sensor circuit for Bank 2 of the engine. This fault is most likely caused by issues with the sensor itself, wiring harness, or in some cases, the PCM (Powertrain Control Module).

P0330 quick overview

Meaning	P0330: Knock Sensor 2 Circuit Malfunction (Bank 2)
Is it serious?	Yes, it can affect engine performance, fuel efficiency, and potentially lead to more severe engine damage if not addressed.
Possible causes	– Faulty knock sensor – Wiring harness issues, including shorts or opens – Corrosion or damage in the sensor harness or connectors – PCM issues, though less common – Oil or sludge buildup affecting the sensor – Aftermarket sensors not compatible or of lower quality
How to diagnose?	Inspect the knock sensor: Look for visible damage or signs of oil/sludge buildup. Check the wiring harness: Examine the wiring leading to the knock sensor for any signs of wear, shorts, or opens. Test the knock sensor: Use a multimeter to check the sensor’s resistance and voltage. Compare the readings to the manufacturer’s specifications. Scan for additional codes: Use an OBD-II scanner to check for other related fault codes that might give more insight into the issue. Check the PCM: Ensure it’s functioning correctly and sending the right signals. This is a less common cause but worth checking if other diagnostics are inconclusive. Inspect sensor connectors: Look for corrosion, damage, or any signs that they might not be making a proper connection. Consider sensor quality: If the sensor was recently replaced, ensure it’s of good quality and compatible with the vehicle.
What is Knock sensor?	A knock sensor is a device that detects engine detonation (knocking) and sends a signal to the engine control unit to adjust timing and prevent engine damage.

How to fix P0330 – learn from mechanics

I looked into P0330 service cases at iatn.com website where in the private forums the mechanics seek advice from other mechanics. I looked up a bunch of cases to help you decide how to fix your knock sensor issue. They also always report the fix that worked for the vehicle so this section will be like having a real mechanic helping you solve your issue.

Case #1: Lexus

Vehicle Information

• 1999 Lexus ES300, 3.0L engine

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Issue + Repair History

• Check engine light and VSC lights on.
• Code: po330
• Previous repair: Scanned car, code p0330 present, cleared codes but light returned after three days.

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Other OBD2 Codes + Test Results

• Only mentioned code: po330 (knock sensor)

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Suggestions from Community

1. Replace both knock sensors and sub harness. Also, replace intake gasket, upper intake gasket, and knock sensor harness. Estimated labor: 4.0 hours.
2. Replace both sensors and sub harness. Remove and reinstall intake manifold. Hand torque the sensors to 28 ft lbs.
3. Replace both sensors and the wiring for the sensors. Also, replace the gaskets.
4. Replace both sensors, the short harness, and reseal the water plate.
5. Check the harness connector behind the back head. After removing the intake, check the connectors at the knock sensors. If okay, replace both knock sensors due to labor involved.

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Final Fix

• Replaced both knock sensors and the new harness. The harness was found to be corroded. Also replaced intake and plenum gaskets. The check engine light turned off after the fix.

Case #2: Ford

2004 Ford F-150 FX4 5.4L Hesitation, MIL Lamp on

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Vehicle Information

• 2004 Ford F-150 FX4, 5.4L engine

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Issue + Repair History

• Vehicle towed in due to lack of power.
• Codes: P0325 and P0330 (both knock sensors failure).
• Test results: 0v on sensor 1 and 1v on sensor 2 (should be 2.5v).
• Vehicle was recently purchased used.

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Other OBD2 Codes + Test Results

• P0325: Knock sensor 1 malfunction
• P0330: Knock sensor 2 malfunction
• Knock sensor 1 wires to PCM: 0v
• Knock sensor 2 wires to PCM: 1v

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Suggestions from Community

1. Knock sensors might be on the same internal circuit in the PCM. A harness short could have affected the PCM drivers.
2. A pinched or deteriorated wire might have caused the short. Check basics like fuel pressure.
3. Unplug the knock sensor. If 5v is detected, the knock sensor is faulty. If not, it could be bad wiring or a bad PCM.
4. Check for wiring issues before considering the PCM. Possible rodent damage. Might need to inspect the harness under the upper intake.
5. Disconnect sensors to see if the 5v reference returns. If it does, reconnect sensors one by one. If not, it’s a wiring or PCM issue. Check for rodent damage.
6. For a 3 valve engine, wires might get pulled apart by the variable intake actuator on the back of the manifold.
7. Ensure sensors are torqued properly.

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Final Fix

• It was a PCM issue. After disconnecting the knock sensor, no voltage was detected from the PCM. The customer decided to address the issue with the dealer.

Case #3: Toyota

Vehicle Information

• 2000 Toyota Avalon XL, 3.0L engine

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Issue + Repair History

• Knock sensor codes P0325 and P0330 detected.
• Wiring from ECM connectors to knock sensors tested and found okay.
• No signs of corrosion, rodent damage, or issues with the intake manifold.
• Both codes seem to set simultaneously within 3-5 minutes of normal driving.
• Recent repair: MAF sensor replaced for a lean code.
• Transmission code P0773 has not reset since clearing.

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Other OBD2 Codes + Test Results

• P0325: Knock sensor bank 1 signal level too low
• P0330: Knock sensor bank 2 signal level too low
• P0773: Shift solenoid E electrical

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Suggestions from Community

1. Test the bios voltage to the knock sensors; PCM might be the issue.
2. Replacing the knock sensor and subharness should resolve P0325 & P0330. For P0773, check the solenoid’s resistance after applying 12 volts multiple times (load test). If knock sensor codes are stored, the transmission won’t shift into O.D.
3. Knock sensors on Toyota V6 engines are commonly problematic.
4. Check if the sensors have any common wires, powers, or grounds.
5. Whenever working around the knock sensor, consider replacing the sub-harness assembly as it’s relatively cheap.

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Final Fix

• Both knock sensors were replaced.
• The harness for the knock sensors was checked and found to be in good condition.
• The vehicle was road tested, and no codes have reset.
• The TCC solenoid issue was explained to the owner, indicating a potential future fix.

Case #4: Mercedes

Vehicle Information

• 1997 Mercedes-Benz C280, 2.8L engine

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Issue + Repair History

• Code P0341 sets while cranking.
• Cam sensor has been replaced.
• Air gap has been checked.
• Engine starts and runs without issues.
• Question raised about a potential variable timing issue.
• Cam sensor was previously replaced.

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Other OBD2 Codes + Test Results

• P0341: Camshaft hall effect sensor
• P0460: Tank fill level too low
• P0330: Knock sensor rear

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Suggestions from Community

1. Check if the engine has been recently assembled. A pre-1997 cylinder head on a 1997 engine might cause the issue due to different cam sprockets.
2. Inspect the harness for insulation issues, as these cars often have harness problems.
3. 1997 might still be a year with engine harness issues for Mercedes-Benz. Check for wire insulation deterioration, especially near coolant switches or where the harness approaches the engine.
4. Scope the sensor at the ECU connection to test both the sensor and wires. Also, check the cam wheel switch.

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Final Fix

• The issue was caused by aftermarket cam sensors.
• After replacing with factory Mercedes sensors, the problem was resolved.

Case #5: BMW

Vehicle Information

• 1998 BMW 540i, 4.4L engine

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Issue + Repair History

• Codes were pulled from pending status, no current codes.
• Engine runs fine currently, but no freeze frame data available.
• Engine struggled to stay running, had a lower engine noise, sounded like it was oil starved.
• Manual oil pressure test showed pressure dropped significantly when the engine revved.
• Cleaned out sludge and screen from the lower pan, changed oil and filter, and the engine runs fine again.

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Other OBD2 Codes + Test Results

• P1384: Manufacturer controlled ignition system or misfire
• P0325: Knock sensor or circuit bank 1
• P0330: Knock sensor or circuit bank 2

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Suggestions from Community

1. Drive the vehicle until codes are set and update the post with freeze frame info. Check for oil in plug wells from leaking valve cover gaskets.
2. Backfire plates might be an issue on these motors. Codes may not be directly related to the customer’s complaint.
3. Check the PCV plate as it might be leaking. Check fuel adaptation when fault code sets freeze frame data. It might be adding fuel to compensate for fuel leaks.
4. Check the PCV plate in the rear as it’s a common issue. Also, inspect the front intake seal and intake gaskets for leaks.
5. Advise the customer about establishing a routine service and maintenance baseline, starting with the PCV and intake gaskets, to troubleshoot drivability problems.

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Final Fix

• Cleaned out sludge and screen from the lower pan.
• Changed oil and filter.
• Engine runs fine after the above steps.