OBD-II Code P0331 — What It Means & How to Fix It

What Does This Error Mean?

P0331 means the knock sensor 2 circuit on Bank 2 is out of its expected operating range. Bank 2 is the side of the engine that does NOT contain cylinder 1 — on a V6 or V8, this is typically the passenger side. The knock sensor is receiving power and sending a signal, but the signal is outside the expected range. This may cause the ECM to use overly conservative ignition timing, reducing power and fuel economy. It won't leave you stranded, but it should be fixed.

Affected Models

V6 and V8 vehicles 1996+
Common in Toyota Tacoma and Tundra V6/V8
Common in Chevrolet Silverado and Tahoe V8
Common in Ford F-150 V6/V8
Common in Honda and Acura V6 models

Common Causes

Loose knock sensor mounting bolt on Bank 2 causing an out-of-range signal
Failed or deteriorating knock sensor on Bank 2 producing incorrect voltage output
Corroded or damaged wiring connector at the Bank 2 knock sensor
Engine oil or coolant leak contaminating the knock sensor mounting area on Bank 2
Wiring issue between the Bank 2 knock sensor and the ECM causing signal distortion

How to Fix It

Confirm the code with an OBD-II scanner and check for any companion codes. P0332 (Bank 2 knock sensor low input) alongside P0331 suggests the sensor or its circuit has a more serious fault. Note the Bank 2 location for your specific engine before beginning work.

Bank 2 is the side without cylinder 1. For most GM V8s, Bank 2 is the passenger side. Consult a service manual if unsure.
Locate the Bank 2 knock sensor. It is typically bolted to the engine block under or near the intake manifold. Check the mounting bolt torque — the sensor must be installed to the manufacturer's specification (usually 15-20 ft-lbs). A loose or overtightened sensor gives an out-of-range signal.

Even a quarter turn of looseness can cause the sensor to underperform.
Disconnect the knock sensor connector on Bank 2 and inspect it for corrosion, moisture, or loose terminals. Clean with electrical contact cleaner. Dry the connector before reconnecting and ensure it locks securely.

Moisture ingress into the connector is a very common cause of range/performance codes.
Test the knock sensor's resistance with a multimeter according to your vehicle's service manual spec. Knock sensors are typically non-resonant piezoelectric sensors with a resistance in the range of several hundred kilohms to several megohms — specs vary widely by manufacturer.

Out-of-spec resistance confirms the sensor needs replacement.
If the sensor tests correctly, inspect the wiring from the Bank 2 sensor to the ECM. Use a multimeter to check continuity and look for shorts. Replace any damaged sections with properly shielded wire if needed.

On some vehicles, both knock sensors share a common ground wire — check that the ground is clean and secure.

When to Call a Professional

Bank 2 knock sensors are often harder to access than Bank 1 sensors, particularly on transverse-mounted V6 engines where Bank 2 faces the firewall. If the sensor is not easily reachable, a shop with the right tools can complete the replacement in 1-2 hours. Always confirm which bank is Bank 2 for your specific engine — it varies by make and model. Expect $150-$400 for knock sensor replacement depending on accessibility.

Frequently Asked Questions

What is the difference between Bank 1 and Bank 2?

On a V-type engine (V6, V8, V10), the cylinders are split into two banks — left and right. Bank 1 is always the side that contains cylinder 1. Bank 2 is the opposite side. Cylinder numbering varies by manufacturer, so Bank 2 could be the driver's side or passenger side depending on your vehicle. Consult your owner's manual or a service guide for your specific engine.

Can I drive with P0331?

Yes, you can drive with P0331. The engine will run, but the ECM may use conservative timing to compensate for the unreliable sensor. This can cause a slight reduction in power and fuel economy. There is no immediate danger of breakdown, but it's worth fixing within a few weeks. Don't use premium fuel as a substitute for fixing the knock sensor — they are separate issues.

Do I need to replace both knock sensors at once?

Not necessarily — only the failing sensor needs replacement. However, if both sensors are original and have high mileage (over 100,000 miles), replacing both at the same time can make sense. Since you're already doing the labor to access one, doing both saves you a repeat job if the other fails soon after.