P0332 on 2020-2025 Audi Q7: Knock Sensor 2 Circuit Low Causes and Fixes

What's Unique About the 2020-2025 Audi Q7

For the 2020-2025 Audi Q7 with the 3.0L V6 TFSI (EA839) engine, the knock sensors are located deep in the engine valley, underneath the intake manifold and supercharger assembly. This location makes replacement a significantly more labor-intensive job compared to engines where the sensors are on the exterior of the block. The code is also specifically mentioned in a Technical Service Bulletin (TSB) that links P0332 and other knock sensor codes to a "Drive System Malfunction" warning on the dashboard, indicating this is a known issue pattern for this powertrain.

Diagnostic Flowchart

Tap your situation to follow the diagnostic path that matches what you're seeing on this vehicle.

Symptoms You May Notice

• Check Engine Light is on
• "Drive System Malfunction" message on the dashboard
• Reduced engine power or vehicle entering "limp mode"
• Hesitation or stumbling during acceleration
• Rough or uneven idle
• Audible engine pinging or knocking (less common, as the system is failing to detect it)
• Inconsistent boost or turbocharger performance

Most Likely Causes

1. Faulty Knock Sensor 2 (Bank 2) 🔴 High Probability → Shop Ignition Knock (Detonation) Sensor The sensor is located in a high-heat, high-vibration area of the engine block, under the intake manifold. Over time, the internal piezoelectric crystal can fail, leading to a low or absent signal.
   How to confirm: After confirming wiring is intact, the easiest method is to swap the Bank 1 and Bank 2 knock sensors. This requires significant labor to access them. If the trouble code changes to P0327 (Knock Sensor 1 Circuit Low), the sensor is confirmed bad.
   Typical fix: Replace the faulty knock sensor. It is highly recommended to replace both knock sensors and the wiring pigtail at the same time due to the high labor cost to access them.
   Est. part cost: $80-$250
2. Wiring or Connector Issue 🟡 Medium Probability Engine heat can make wiring and connectors brittle. Rodents are also known to chew on the soy-based wiring insulation. The harness is tucked into the engine valley, making visual inspection difficult without disassembly.
   How to confirm: Visually inspect the wiring harness leading to the knock sensor on Bank 2. Look for breaks, corrosion, melting, or signs of rodent damage. Check for a secure connection at the sensor and at the ECM. This will require removing the intake manifold.
   Typical fix: Repair the damaged section of the harness or replace the connector pigtail.
   Est. part cost: $20-$50
3. Improperly Torqued Knock Sensor ⚪ Low Probability → Shop Ignition Knock (Detonation) Sensor This is more likely to occur after recent engine work. The sensor is a microphone that must be torqued to a specific value to 'hear' engine vibrations correctly. If it's too loose or too tight, it won't function properly.
   How to confirm: Check the sensor's mounting bolt. If it is loose, this is the likely cause. This requires accessing the sensor.
   Typical fix: Torque the knock sensor to the manufacturer's specification, which is typically 20 Nm for many Audi engines.
   Est. part cost: $0

Rare But Worth Checking

• Powertrain Control Module (PCM) Fault: This is very rare. Before condemning the PCM, all other possibilities, especially sensor and wiring issues, must be exhaustively ruled out.
• Other Engine Component Failures: Occasionally, a fault in a nearby component can cause the code. One forum user reported that a broken vacuum line blowing on the knock sensor harness was the root cause of P0327 and P0332 codes.

Diagnosis Steps

1. Verify the code with an OBD-II scanner. 🎬 Watch: Understanding low input codes P0327 and P0332 Note any other codes present.
2. Clear the codes and perform a test drive to see if P0332 returns immediately.
3. Acknowledge that physical access to the sensor and wiring requires removal of the intake manifold/supercharger assembly. This is a significant job.
4. Once accessed, locate Knock Sensor 2 on Bank 2. For a V6 engine, Bank 2 is the driver's side (left side) of the engine in North America.
5. Perform a thorough visual inspection of the sensor's wiring harness and connector for any signs of damage, melting, or corrosion.
6. Check for a loose sensor mounting bolt. Ensure it is torqued to specification (e.g., 20 Nm).
7. If possible, swap the knock sensors between Bank 1 and Bank 2. Clear the codes and rescan. If the code changes to P0327 (Bank 1), the sensor you moved is faulty. Given the labor, it is recommended to replace both sensors regardless.
🎬 See this walkthrough on fixing a P0332 code
8. If the code remains P0332 after swapping the sensor, the fault lies in the wiring harness or the ECM.
9. Use a multimeter to test for continuity and check for a short to ground in the wiring harness between the sensor connector and the ECM.

Parts You'll Likely Need

• Knock Sensor (OEM #06M905377) — This is the most common component to fail. The part number for the 2020+ Q7 appears to be 06M905377. An earlier number, 06E905377M, may also be used on related engines. It is best practice to replace both sensors at the same time.
  Trusted brands: Genuine VW/Audi, Bosch, NTK
  OEM price range: $50-$90
  Aftermarket price range: $40-$70
• Knock Sensor Wiring Harness/Pigtail — Often replaced as a preventative measure, as the plastic and wiring can become brittle from engine heat and cause intermittent connections. Given the labor to access the sensors, replacing the harness is cheap insurance.
  Trusted brands: Bosch, Genuine VW/Audi
  OEM price range: $40-$70
  Aftermarket price range: $20-$40
• Intake Manifold Gaskets — These are required for re-installing the intake manifold/supercharger after accessing the knock sensors. They are single-use and must be replaced. 🎬 Watch: How to carbon clean valves while the manifold is off
  Trusted brands: Genuine VW/Audi, Victor Reinz
  OEM price range: $50-$100
  Aftermarket price range: $30-$60

Related Codes That Often Appear With This One

• P0327 — Knock Sensor 1 Circuit Low. Seeing both codes could indicate a shared wiring problem, a faulty harness, or a coincidental failure of both sensors.
• P0328 — Knock Sensor 1 Circuit High. As mentioned in TSB_2081342_1, various knock sensor codes can appear together.
• P0333 — Knock Sensor 2 Circuit High. This can appear with P0332 if there's an intermittent wiring short or sensor failure.

Technical Service Bulletins (TSBs) & Recalls

• TSB_2081342_1: Provides information for a Drive System Malfunction warning related to knock sensor DTCs P0327, P0332, P0328, and P0333 on V6 TFSI engines.

Platform-Specific Known Issues

• A known Technical Service Bulletin (TSB_2081342_1) exists for the V6 TFSI engine, which acknowledges that a "Drive System Malfunction" warning can be caused by DTCs P0332, P0327, P0328, and P0333.
• The knock sensors are located under the intake manifold/supercharger, making replacement a labor-intensive job requiring several hours of disassembly and reassembly.
• The "Drive System Malfunction" light, while associated with this TSB, is a generic warning on this platform and can also be triggered by more serious issues like the failure of the Belt Starter Generator (BSG) on the 48V mild-hybrid system.

Mechanic-Grade Diagnostic Values

• Knock Sensor Mounting Bolt Torque — expected: 20 Nm. Failure: An incorrect torque value can impair the sensor's ability to detect vibrations correctly.
• Knock Sensor Signal Voltage (Live Data) — expected: Typically 0-5mV at idle, increasing with RPM and load.. Failure: A reading that is stuck at zero or is significantly lower than other cylinders under the same conditions points to a circuit low issue.

Hidden / Shadow Codes Worth Checking

• 16716: This is the VAG-specific fault code that corresponds to the generic OBD-II code P0332. It is described as "Knock Sensor 2 (G66): Signal Too Low". (see via This code is visible using VW/Audi-specific scan tools like VCDS (VAG-COM) or ODIS.)

Scan Tool Commands That Help

• VCDS (VAG-COM): Engine -> Measuring Blocks, Groups 020-028 — Use these blocks to monitor live knock sensor voltage and ignition timing retard per cylinder. Group 026 specifically shows the knock sensor voltage for cylinders 1-4, and Group 027 for cylinders 5-8. Comparing the voltage from the sensor on Bank 2 (G66) to the sensor on Bank 1 (G61) can help identify a weak or dead sensor.
• VCDS (VAG-COM) or ODIS: Engine -> Basic Settings -> Group 028 (Knock Sensor Test) — This function performs a self-test of the knock sensor circuit. The procedure typically requires holding the brake and accelerator pedals to the floor while the ECU runs the test at a limited RPM (e.g., 2000-2500 RPM). A result of "Sys. not OK" indicates a failure in the circuit being tested.

Wiring & Ground Locations

• Knock Sensor 2 (G66) Connector — In the engine valley, under the intake manifold/supercharger assembly, on the driver's side (Bank 2) of the engine block.. This is the primary connection point for the sensor. It is susceptible to heat damage, corrosion, and being improperly seated, all of which can cause a 'Circuit Low' fault.
• Engine Block Ground — The knock sensor grounds through its mounting bolt to the engine block.. A poor ground connection due to corrosion, dirt, or an improperly torqued bolt can disrupt the sensor's signal, leading to a P0332 code. The mounting surface must be clean for a proper connection.

Real Owner Repair Stories

• AudiWorld Forums user 'TTschwing' (Audi TT (different model, but same codes and relevant principle)) — Check Engine Light with codes P0327 (Knock Sensor 1 Circuit Low) and P0332 (Knock Sensor 2 Circuit Low).
  ❌ Tried (didn't work) Initial plan was to remove and clean the knock sensors.
  ✅ What actually fixed it The user discovered a broken vacuum line near the knock sensor wiring harness. The leak from the hose was blowing directly onto the harness connector. Replacing the broken vacuum line resolved both knock sensor codes.

Model Year Variations Within This Range

• 2018-2020: Early versions of the EA839 3.0T engine (used in S4/S5/SQ5 and related platforms before/during the Q7's adoption) had a known issue with rocker arm failures. While not a direct cause of P0332, significant engine vibrations or internal engine problems resulting from such a failure could potentially trigger knock sensor codes. This is less of a concern for later 2021+ models.