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P0325 on a 2017 Chevrolet Tahoe

Knock Sensor 1 Circuit Fault

Severity: moderate Safe to drive (short term) Full-size SUV 2015-2019 Chevrolet Tahoe

What does P0325 mean on a 2017 Chevrolet Tahoe?

P0325 is set when the engine control module does not receive a valid signal from the Bank 1 knock sensor — or the only knock sensor on engines that use one. The knock sensor is a piezoelectric vibration sensor that listens for the characteristic frequency of pre-ignition (detonation) so the ECM can pull timing to protect the engine. With no usable knock signal, the ECM defaults to conservative timing maps, which reduces power and fuel economy.

Symptoms on a 2017 Chevrolet Tahoe

Likely causes on a 2017 Chevrolet Tahoe

  1. Failed knock sensor element Most common
    Estimated repair: $150– $600

    Most common at 100k+ miles. Some engines bury the sensor under the intake.

  2. Damaged or corroded knock sensor wiring or connector Common
    Estimated repair: $80– $350
  3. Loose knock sensor mounting (sensor must be torqued correctly to "hear") Common
    Estimated repair: $20– $100
  4. Rodent damage to knock sensor harness (parked vehicles) Occasional
    Estimated repair: $80– $350
  5. Failed knock sensor sub-harness on GM L83/L86 truck V8s Occasional
    Estimated repair: $200– $600

    Specific to GM 5.3 / 6.2 truck V8s — well-documented sub-harness failure.

  6. Internal engine damage producing noise outside the knock sensor band Rare
    Estimated repair: $2,000– $6,000

How to diagnose this on a 2017 Chevrolet Tahoe

  1. Locate the knock sensor — often under the intake manifold

    On many engines (notably GM V6 + V8 truck engines, Toyota 2GR-FE, and most modern Hondas) the knock sensor sits in the engine valley under the intake manifold. Knowing this before starting saves a wasted hour of looking. Consult the service manual.

    Tools: Vehicle-specific service information

  2. Test knock sensor resistance

    Unplug the sensor and measure resistance with a multimeter. Most knock sensors read approximately 90 kΩ to 2.5 MΩ depending on style. Infinite resistance (open) or near-zero (short) confirms a failed sensor.

    Tools: Multimeter, Service spec sheet

  3. Inspect the wiring and connector

    Knock sensor harnesses run close to hot exhaust components and are common chafing victims. Inspect every inch of the harness from the sensor to the PCM connector. Repair any visible damage before replacing the sensor.

    Tools: Inspection mirror, Flashlight, Wire repair supplies

  4. Verify torque specification on the existing sensor

    A knock sensor mounted with the wrong torque cannot transmit vibration efficiently. Spec is typically 15–25 ft-lb. Use a torque wrench, not "tight by feel." Over-torque can crack the housing; under-torque produces false knock-sensor codes.

    Tools: Torque wrench, Service spec sheet

  5. Check for GM-specific sub-harness failure

    On GM L83 (5.3 V8) and L86 (6.2 V8) truck engines, the knock sensor sub-harness running under the intake manifold is a documented failure point — the harness chafes and shorts. Replacement requires intake manifold removal. The sub-harness itself is inexpensive but the labor is significant.

    Tools: Intake manifold gasket, Common hand tools

Common fixes

About the 2015-2019 Chevrolet Tahoe

The 2015-2019 Chevrolet Tahoe was commonly sold with the following powertrains: 5.3L V8, 6.2L V8, 3.0L Duramax I6 Diesel. Common trims include LS, LT, RST, Premier, High Country.

Why P0325 is a “common” code on GM V8 trucks

GM L83 (5.3L) and L86 (6.2L) Gen V V8 engines — used in 2014+ Silverado, Sierra, Tahoe, Yukon, Suburban, and Escalade — have a well-documented knock sensor sub-harness failure. The harness chafes against the intake valley pan and eventually shorts. P0325 + P0330 setting together on these engines is so common that aftermarket “extended” sub-harnesses are sold specifically to relocate the wiring away from the chafe point.

If you have one of these vehicles, expect this repair around 80–130k miles. Plan it with the next intake manifold service.

What the ECM does without a working knock sensor

The engine still runs — but conservatively. The ECM uses “open-loop” ignition timing maps that pull 3–6 degrees of advance out of every cell, sacrificing power and fuel economy to ensure no detonation. Expect 1–2 MPG lower and noticeably slower throttle response.

Knock sensor diagnostics with a scope

The knock sensor is essentially a microphone. Tapping the cylinder block near the sensor with a screwdriver while watching the scan-tool knock count PID should produce hits. No response to tapping confirms a dead sensor or open wiring even if the multimeter resistance looks correct.

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