Fix P0333: Mechanic’s solutions that WORKED

The P0333: Knock Sensor 2 Circuit High Input code indicates an issue with the second knock sensor, specifically a high input signal. This sensor is crucial for detecting engine knock or pinging, which can cause damage. The ECM uses this information to adjust the engine’s timing and prevent damage. A high input signal can mean the sensor is malfunctioning or the engine is experiencing undue stress or mechanical issues.

P0333 quick overview

Meaning	P0333: Knock Sensor 2 Circuit High Input
Is it serious?	This code can be serious as it may lead to engine damage due to improper engine detonation control.
Possible causes	– Faulty or damaged knock sensor – Wiring issues (damaged, corroded, or disconnected) – Incorrectly installed or timed engine components – Engine mechanical noise (e.g., due to wear or damage) – Issues with the Engine Control Module (ECM)
How to diagnose?	Inspect Knock Sensor: Check the condition of the knock sensor on Bank 2 for damage or wear. Check Wiring and Connections: Examine the sensor wiring for damage, disconnections, or corrosion. Verify Engine Timing: Ensure the timing belt or chain is correctly installed and timed. Analyze Sensor Signal: Use a multimeter or oscilloscope to test the knock sensor signal. Inspect Related Components: Look for related issues such as damaged engine components that could cause noise. Evaluate ECM Function: Consider if there could be a problem with the ECM affecting sensor readings. Oil Quality and Pressure: Check the engine’s oil quality and pressure, as these can impact sensor function.

How to fix P0333 – learn from mechanics

I looked into P0333 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 issue and see what would a real mechanic do to solve it.

Case #1: Toyota

Vehicle Information: 2008 Toyota Tacoma 4.0L

Issue + Repair History:

• Code P0333 “Knock Sensor 2 Circuit High Input (Bank2)” was present.
• Access to knock sensors was challenging; thought to require removal of the camshaft and engine head.
• Found wires cut by mice upon inspection.

Computer Codes & Descriptions:

• P0333: Knock Sensor 2 Circuit High Input (Bank2)

Suggestions to Fix Issue:

• Inspect the wire harness of the knock sensor for damage, particularly from rodents.
• Check sensor signal wire voltages and resistance.
• Examine the EE1 connector at the back of the cylinder head.
• Apply pressure or vacuum to the sensor to test its operation.
• Look for signs of rodent damage or nests near the sensor.

Final Fix:

• Removed the planum chamber and lower intake manifold to access knock sensors.
• Discovered wires were cut by mice.
• Replaced the sensor wire set and fixed the issue.

Case #2: Jaguar

Vehicle Information: 1997 Jaguar XK8 4.0L

Issue + Repair History:

• MIL Lamp on with codes P0328 and P0333.
• Found unusual voltage readings at knock sensor pins and the computer (PCM).
• Tested for shorts but found none.
• Two new knock sensors were installed prior to the issue.

Computer Codes & Descriptions:

• P0328: KS Sense Circuit Out of Range (High Voltage) A Bank
• P0333: KS Sense Circuit Out of Range (High Voltage) B Bank

Suggestions to Fix Issue:

• The signal voltage on knock sensors should be close to 2.40-2.49V, either KOEO or KOER.
• Check if there’s anything common to both knock sensors, like melted wires.
• Test knock sensor functionality by tapping on the block to simulate a knock and observing timing changes.
• Consider the possibility of an issue with the PCM, especially in light of unusual voltage readings.

Final Fix:

• Discovered a blown capacitor inside the ECM.
• Cleaned the circuit board and replaced the capacitor.
• This resolved the issue, indicating the capacitor and possible dielectric shorting were the causes.

Case #3: Volvo

Vehicle Information: 2001 Volvo V70 2.4T 2.4L

Issue + Repair History:

• MIL Lamp on with codes ECM-3420 / P0333 and other knock sensor-related codes.
• Replaced knock sensors and rechecked with Vida diagnostic tool.
• Codes persisted, indicating high signal from rear knock sensor.
• Checked fuel trim and pending faults with a generic scan tool.

Computer Codes & Descriptions:

• ECM-3420: Permanent fault rear knock sensor signal high
• ECM-3410: Intermittent fault front knock sensor signal high
• ECM-4801: Three-way cat efficiency bank 1
• ECM-201A: Thermostat faulty signal

Suggestions to Fix Issue:

• Check the fuel grade being used in the vehicle.
• Consider the possibility of mechanical engine noise or an internal rattle in the catalytic converter.
• Verify the operation of the knock sensors under different engine conditions.
• Replace the thermostat and retest.
• Check for any issues common to both knock sensors, such as melted wires or a faulty ECM.

Final Fix:

• Found a loose injector connector causing the car to lean out under hard acceleration.
• Securing the connector resolved the knock sensor code and other related issues.
• Thermostat replacement addressed the ECM-201A code.
• Customer advised to monitor the catalytic converter due to ECM-4801 code.

Case #4: Lexus

Vehicle Information: 2005 Lexus GX470 4.7L

Issue + Repair History:

• Initially replaced a knock sensor for code P0333.
• After repair, encountered a new code P0331.
• Planning to open up the intake again to check wires for continuity.

Computer Codes & Descriptions:

• P0331: Knock Sensor Circuit / Performance Bank 2

Suggestions to Fix Issue:

• Check connections and continuity to the other knock sensor.
• Consider replacing both knock sensors and their wiring harness due to potential brittleness from heat/age.
• Ensure that connectors and clips on the knock sensor are intact and not disconnected.
• Check all ground connections related to the knock sensors.

Final Fix:

• Found that wires to the replaced knock sensor had been chewed by mice.
• Repaired the damaged wire, which solved the problem.

Case #5: Cadillac

Vehicle Information: 2010 Cadillac SRX Luxury 3.0L

Issue + Repair History:

• Vehicle experienced no power under initial load but ran fine afterwards.
• No misfire codes but seemed to be missing on takeoff.
• Related repair history includes new timing chains.

Comments Update:

• Harness feeding bank 2, knock sensor, and O2 sensors were found to be unplugged.

Computer Codes & Descriptions:

• P0050: HO2S Control Circuit Bank 2 Sensor 1
• P0333: Knock Sensor Bank 2
• P06B7: Control Module Knock Sensor Processor 2 Performance
• P0157: HO2S Circuit Low Voltage Bank 2 Sensor 2

Other Test Results:

• Exhaust Restriction: Pulling O2 sensor didn’t improve response on takeoff.
• Throttle Actuator: Checked and read properly on scan tool.

Suggestions to Fix Issue:

• Focus on resolving knock sensor and O2 sensor issues.
• Check if timing chains are properly installed and timed.
• Investigate the wiring harness, especially around the knock sensors and O2 sensors, for pinches or disconnections.

Final Fix:

• The issue was resolved after discovering and reconnecting the unplugged wiring harness, significantly improving vehicle performance.

Advice	Description of Diagnostic Step
Check Wiring Harness	Inspect the wiring harness for any damage, disconnections, or signs of rodent infestation.
Inspect Knock Sensors	Verify the condition of the knock sensors and replace if necessary. Use OEM parts for best results.
Confirm Proper Timing	Ensure that the timing chain or belt is correctly installed and timed, especially after recent repairs.
Test Sensor Signal	Use a multimeter or oscilloscope to check the knock sensor signal for proper voltage and response.
Investigate Related Codes	Look into any related diagnostic trouble codes that might be affecting the knock sensor circuit.
Check for Mechanical Noise	Identify any unusual mechanical noises from the engine that could be triggering the knock sensor.
Examine ECM/PCM	Consider the possibility of an issue with the Engine Control Module or Powertrain Control Module.
Oil Pressure and Quality	Check oil pressure and quality, as low oil pressure can affect engine performance and sensor readings.
Assess Engine Condition	Evaluate the overall condition of the engine, including checking for sludge buildup or wear.