OBD-II trouble code
P0332: Knock Sensor 2 Circuit Low Input (Bank 2)
The second knock sensor — the one on bank 2 — is reporting signal voltage below the PCM's minimum threshold. If you've already read about P0327, this is the same failure on the opposite cylinder bank: the PCM has effectively gone deaf on that side and falls back to a conservative timing map.
Quick facts
- System
- Powertrain
- Category
- Knock & Other
- Severity
- Medium severity
- Drivable
- Usually safe to drive short-term
- Repair cost range
- $150 – $800
- DIY difficulty
- Intermediate DIY
Browse every code in P0300–P0394, or start from the full code library.
What does P0332 mean?
P0332 is the bank-2, low-input member of the knock sensor family, and the first thing to sort out is which physical sensor it points to. A knock sensor is a piezo accelerometer bolted to the engine block that listens for detonation — combustion firing too early — so the PCM can retard timing to protect the engine. On a V engine with two knock sensors, sensor 2 is on bank 2, the bank that does not contain cylinder 1. Which fender that is depends on the engine and on how it is installed. It is not the same on every V engine.
On a GM LS V8, bank 1 is cylinders 1-3-5-7 and bank 2 is 2-4-6-8 (LS Engine DIY, GM Gen III firing order). On a longitudinal GM truck that puts cylinder 1 on the driver side, so bank 2 is the passenger side. On a Ford Modular V8, cylinders 1-4 are on the passenger side and 5-8 on the driver side (Summit Racing, Ford Modular firing order), so bank 2, the bank without cylinder 1, is the driver side. Confirm cylinder 1 on the vehicle. A transverse installation swaps which fender is the driver side, and on a transverse V6 the banks are often the front and the rear rather than the left and the right.
The 'low input' part means the signal voltage on the bank-2 knock sensor circuit has dropped below the minimum the PCM expects — the direct mirror of P0327 on bank 1. The sensor, a shorted wire, and a corroded connector are three results that produce that low. Knock sensors are a wear item: the piezo crystal degrades with years of heat and vibration, so age and accumulated thermal cycling matter more here than mileage alone.
A known platform for this code is the 1999-2007 GM LS-family truck and SUV engines — the 4.8L, 5.3L, and 6.0L in Silverado, Sierra, Tahoe, Yukon, Suburban, and Avalanche. Some of those knock sensors sit in the valley under the intake, where water can pool on the sensor and the connector. Look that location up on the diagram for the engine in front of you. Where the diagram puts both sensors in that valley, the intake comes off to reach either one.
Driveability symptoms are subtle because knock sensing is a protection layer, not a load-bearing system. The engine still runs, but it loses the smart ignition advance it would normally make, so you get a slight drop in power and fuel economy. The real long-term risk is that genuine detonation on bank 2 now goes undetected, which under heavy load or low-octane fuel can damage pistons or bearings.
Common causes
- Failed bank-2 knock sensor — piezo element degraded internally
- Corroded bank-2 knock sensor on a GM LS truck whose diagram places the sensor in a well under the intake
- Signal wire shorted to ground on the bank-2 circuit
- Corroded or damaged bank-2 knock sensor connector
- Loose knock sensor — proper torque matters because the sensor relies on mechanical coupling to the block
- Aftermarket knock sensor of incorrect specification
- Wiring chafe along the valley or block on the bank-2 harness run
- PCM signal-input fault (rare)
Symptoms
- Check engine light on with P0332 stored
- Mild loss of power, especially under acceleration
- Reduced fuel economy
- Slightly delayed throttle response
- Possible audible pinging under heavy load if real detonation goes undetected on bank 2
- Engine sounds and runs normally in most cases
Diagnostic steps
- 1.Confirm which physical bank is bank 2 on this vehicle — the head that does not contain cylinder 1. On a longitudinal GM LS truck, cylinder 1 is on the driver side, so bank 2 is the passenger side. On a Ford Modular V8, cylinders 1-4 are on the passenger side, so bank 2 is the driver side. A transverse installation can put that bank on the other fender. Use the firing-order diagram for this engine.
- 2.Pull all codes. P0332 alone is the classic bank-2 sensor failure. P0332 alongside P0333 or the bank-1 codes (P0327/P0328) can point at shared wiring or a PCM-side issue.
- 3.On a GM LS truck, look up where the knock sensors sit. If the diagram puts them under the intake, plan for the manifold to come off and check the wells for water before condemning the sensor.
- 4.Disconnect the bank-2 knock sensor connector and measure resistance across the terminals against the figure for that exact part. An open or near-zero reading confirms a failed sensor. A reading inside the range does not clear it: a piezo element usually fails by losing output sensitivity rather than by changing resistance, so this test can condemn a sensor but cannot exonerate one.
- 5.Test the sensor's actual output before moving on. Watch the knock signal or knock retard value on a scan tool while tapping the block near the sensor with a small wrench at idle. A good sensor responds visibly; one that measures in range and produces nothing is the failure a resistance check walks straight past.
- 6.Check harness continuity with both ends disconnected, measuring across the conductor itself. Back-probing a connected circuit reads the path through the sensor rather than the wire, so it cannot prove the harness is intact — back-probe to watch the live signal, not to test continuity. Check separately for a short to ground with the circuit isolated.
- 7.Inspect the connector for green corrosion, oil contamination, or pushed-back pins.
- 8.When replacing, torque the sensor to spec — too loose and it can't read block vibration, too tight and the piezo crystal can crack. If both sensors are reached by the same intake removal, replacing the second one is a parts decision made while the manifold is off.
- 9.Clear the code, drive through a heavy-load condition such as a highway on-ramp, and confirm it stays off.
Repair cost
$150 – $800
A knock sensor the diagram shows in the open, or a wiring repair you can reach, is the inexpensive repair. A sensor the diagram places under the intake is the expensive one, because the manifold comes off. Take the printed numbers as a planning span, not as a quote. Price the sensor you can see, or the intake job the diagram requires, plus the labor the service information assigns to this vehicle. A GM truck knock sensor is sometimes down in the valley. Read the diagram before the intake is scheduled.
Estimate your repair
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Open the Repair Cost Estimator with knock sensor replacement preselected. Adjust labor rate and vehicle category to fit your situation.
Related repairs
DIY vs shop
This is an intermediate DIY job. It usually involves diagnostic steps, specialty parts, and some careful work in tight spaces. If you have the tools and a service manual or trustworthy video for your specific vehicle, it is achievable in a weekend. Otherwise, a competent independent shop will be faster.