P0330: How to Diagnose & Fix — Knock Sensor 2 Circuit (Bank 2)
6 vehicles · 5 makes · $150-$1,200 repair
How to diagnose and fix P0330: most-reported vehicles
Ranked by owner reports. Each card gives the symptoms, how to confirm the cause, the fix, parts and sources for that vehicle.
Lexus ES · 1997–2003
On the 1MZ-FE V6 the two knock sensors sit in the valley between the cylinder heads, and their sub-harness bakes there under the intake manifold. The wire insulation hardens and chafes, shorting the signal wire to ground and setting P0325 (knock sensor 1 circuit) and/or P0330 (knock sensor 2 circuit). The ECU responds by pulling timing, so the car runs down on power and mileage with a permanent check engine light. The recurring forum lesson is that the harness - not the sensors - is usually the failed part: owners who replace only the sensors see the code return within days.
Common Symptoms
- Check engine light with P0325 and/or P0330
- Reduced power and sluggish acceleration from retarded timing
- Worse fuel economy
- Codes return shortly after replacing only the knock sensors
How to Fix
Replace both knock sensors AND the knock sensor sub-harness with genuine Toyota parts as a set; the intake manifold has to come off either way, so doing the harness at the same time is nearly free labor. Skipping the sub-harness is the single most common reason the code comes back. If codes persist after both, check the ECU ground straps and the connector pins for corrosion before condemning anything mechanical.
Sources for this issue (3)
GMC Sierra 1500 · 2000–2006
The 4.8L, 5.3L, and 6.0L Vortec engines used in early GMT800 Sierra trucks place the knock sensors in wells beneath the intake manifold, where water can collect and corrode the sensors or harness. Owners frequently report recurring check-engine lights, timing retard, and reduced power, especially after washing the engine bay or driving in wet conditions. GM issued service information addressing knock sensor corrosion and revised sealing practices.
Common Symptoms
- check engine light
- reduced power
- poor acceleration
- intermittent spark retard
- codes return after rain or washing
- rough running under load
How to Fix
Diagnosis involves scanning for knock sensor circuit codes, checking freeze-frame data, and inspecting the sensor wells and sub-harness under the intake for moisture or corrosion. Proper repair is replacement of both knock sensors and the harness, cleaning the valley area, and resealing the intake and sensor openings with the updated grommets/sealant procedure to prevent repeat failures.
Sources for this issue (1)
Chevrolet Silverado 1500 · 2000–2006
On 4.8L, 5.3L, and 6.0L GMT800 V8 trucks, the valley-mounted knock sensors and harness are prone to water intrusion from the cowl/intake area. Moisture corrodes the sensors or harness connectors, leading to false knock readings, a check engine light, and timing retard that can make the truck feel sluggish. This is one of the best-known early Silverado engine electrical issues and is heavily documented by owners and repair shops.
Common Symptoms
- check engine light
- reduced power or sluggish acceleration
- poor fuel economy
- intermittent spark knock timing retard
- engine runs normally but stores knock sensor codes
How to Fix
Diagnosis should confirm sensor circuit faults and inspect the harness and sensor wells for corrosion or standing water. Repair typically includes replacing both knock sensors, the sub-harness, intake gaskets, and the rubber seals/grommets, while cleaning the valley and addressing any water entry path. Using dielectric protection and updated sealing practices helps prevent repeat failures.
Sources for this issue (1)
GMC Yukon XL · 2000–2006
Toyota 4Runner · 1996–2002
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P0330 code reference
General diagnostic-code context. The code alone does not confirm a cause for your vehicle; use the applicable issue card and its sources.
Frequently asked questions
What does P0330 mean?
P0330 stands for "Knock Sensor 2 Circuit (Bank 2)." This powertrain code means the engine computer detected a malfunction in the circuit for knock sensor 2, located on engine bank 2 (the cylinder bank not containing cylinder 1). The knock sensor listens for engine 'knock' or 'ping' (abnormal combustion) and lets the computer retard ignition timing to prevent engine damage. This code indicates an electrical/circuit problem with the sensor signal, not necessarily actual knocking. Drivability is often normal, but the engine may run with conservative timing, reducing power and economy and risking damage if real knock occurs.
What are the most common causes of P0330?
The most common causes of P0330 are: Faulty knock sensor on bank 2, Damaged or corroded knock sensor wiring/connector, Open or short in the knock sensor circuit, Loose or improperly torqued knock sensor, Engine ground or shielding issues affecting the signal, Faulty engine control module (rare). The specific cause varies by vehicle.
How much does it cost to fix P0330?
Repair costs for P0330 range from $150 to $1,200, depending on the vehicle and root cause.
Which vehicles are affected by P0330?
Au7o has documented P0330 across 6 vehicle models from 5 manufacturers: Chevrolet, GMC, Hyundai, Lexus, Toyota.
Content compiled with AI assistance using NHTSA complaints, TSBs, and owner reports. May contain errors. Always verify with your vehicle's service manual.