P0333
UniversalKnock Sensor 2 Circuit High Input (Bank 2)
Medium SeverityThe knock sensor on Bank 2 is sending an unusually high voltage signal to the engine's computer, indicating a potential circuit issue rather than actual engine knocking. This can cause the engine to operate with a retarded ignition timing, leading to reduced power and fuel efficiency to prevent perceived engine damage.
⚠️ Before You Begin (Safety First)
Always disconnect the battery before performing any electrical repairs to prevent accidental short circuits or injury. Allow the engine to cool down completely before working near hot components.
Common Symptoms
- Check Engine Light illumination
- Reduced engine performance
- Decreased fuel economy
- Engine pinging or knocking (less likely if it's a circuit high input, but possible if the sensor is misreporting)
- Engine running rough
Common Causes
- Faulty knock sensor (internal short)
- Damaged or shorted wiring harness to the knock sensor (shorted to voltage)
- Corroded or loose electrical connectors at the knock sensor or PCM
- Faulty Powertrain Control Module (PCM) (rare)
Frequently reported on: Toyota Camry V6 (2002-2006), Honda Pilot (2003-2008), Chevrolet Silverado 1500 (2007-2013), Lexus RX 300 (1999-2003), Ford F-150 V8 (2004-2008)
Diagnostic Steps
- Visually inspect the knock sensor wiring harness for any signs of damage, fraying, or shorting to power sources.
- Check the electrical connector at the knock sensor and the PCM for corrosion, bent pins, or a loose connection.
- Using a multimeter, test the voltage at the knock sensor circuit to confirm a high input signal (refer to service manual for specific voltage ranges).
- If accessible, disconnect the knock sensor and re-check the circuit. If the high input disappears, the sensor is likely faulty.
- Replace the faulty knock sensor, ensuring it is torqued to specifications.
- Clear the DTCs and test drive the vehicle.
👨🔧 When to Call a Professional
If diagnostic steps confirm a faulty knock sensor or wiring issue, and you are uncomfortable with accessing the sensor (especially if it's under the intake manifold), it is best to consult a professional mechanic.
Commonly Asked Questions
Can I drive with a P0333 code?
It's advisable to get it checked soon. While not always an emergency, prolonged driving with this code can lead to reduced engine performance and fuel economy, and may prevent the engine from properly detecting actual knocking.
What is "Bank 2"?
In a V-type engine, "Bank 2" refers to the cylinder bank that does not contain cylinder #1.
How do I test a knock sensor?
A common test involves checking the sensor's resistance with a multimeter and monitoring its voltage output while tapping near the sensor or running the engine. Consult your vehicle's service manual for specific values and procedures.
Is a P0333 code always a bad knock sensor?
Not always. While a faulty sensor is a common cause, the code specifically points to a "circuit high input," which could also be due to damaged wiring (shorted to voltage), corroded connectors, or, less commonly, a PCM issue.
Will replacing the knock sensor fix my performance issues?
If the knock sensor or its circuit was indeed the cause of the code and your engine's retarded timing, then replacing it should restore normal engine performance and fuel efficiency.