P0332: Knock Sensor 2 Circuit Low Input (Bank 2)

What is P0332?

Fault code P0332 is defined as “Knock Sensor 2 Circuit Low Input (Bank 2).” This diagnostic trouble code gets logged when the engine control module (ECM) receives a low input signal from the #2 knock sensor circuit.

How does that happen?
The knock sensor 2 circuit is mounted on the engine block. It’s designed to detect an engine knock (spark knock), which is a pinging or knocking sound caused by abnormal combustion in the engine.

When this happens, the sensor sends the data to the ECM and uses this information to retard (adjust) ignition timing, preventing potential engine damage. 

But if you have a “Knock Sensor 2 Circuit Low Input” error, it indicates that the sensor output signal is below the manufacturer’s specified range. 

As a result, the engine control module may not receive accurate signals when the air and fuel combust early. Consequently, it won’t be able to adjust the ignition timing.

Common Symptoms

Apart from pinging and knocking sounds, here are a few tell-tale signs of P0332 DTC :  

1. An Illuminated Check Engine Light

The check engine light (CEL) flashing on your dashboard is the first noticeable symptom for any engine code, including DTC P0332 and P0327 (knock sensor error codes). 

It comes on when the ECU detects a low input signal from the knock sensor, wiring issues, or even a problem with the ECU itself.

However, you’ll need an OBD2 scan tool to help determine the exact cause of the lit check engine light on your dashboard. 

2. Sudden Loss of Engine Power

A faulty knock sensor fails to accurately detect and relay signals to the ECU, preventing it from adjusting the ignition timing properly. This can result in the spark plug igniting the air-fuel mixture late.

When combustion is delayed, the engine can’t fully burn the air-fuel mixture. This leads to reduced engine power, decreased efficiency, and potential performance issues.

3. An Overheated Engine

Your engine can overheat from faulty ignition timing going undetected by a bad knock sensor. However, it could also happen when you have a faulty serpentine belt or engine cooling system.

So, it’s best to have an auto repair professional diagnose the issue and determine whether trouble code P0332 is causing it.

4. Increased NOx Emissions

An engine problem due to a faulty knock sensor circuit can damage your vehicle’s catalytic converter.

If the catalytic converter fails, your engine can’t convert toxic pollutants into less harmful emissions, resulting in your vehicle failing the emissions test.

Important information: Increased NOx emissions could also be due to a negative fuel trim caused by a bad O2 sensor. 

5. Decreased Fuel Efficiency

A problem in your vehicle’s ignition timing or fuel trim can make your engine burn more fuel to propel the car forward, resulting in fuel consumption spikes.

However, a drop in fuel efficiency can also be due to other issues like worn spark plugs, so a professional diagnosis is necessary.

P0332 causes

Here are some possible causes of code P0332:

1. Defective knock sensor or knock sensor circuit
2. Damaged knock sensor wire or connector
3. Lean air-fuel ratio
4. Malfunctioning engine cooling system or exhaust gas recirculation (EGR) system
5. Faulty engine control module

How Serious is Code P0332 & Can I Still Drive?

Fault code P0332 may not pose an immediate drivability issue, but it shouldn’t be ignored. This engine code is logged when the knock sensor is offline, not when the actual engine knocking occurs.

However, without a functioning knock sensor, the ECM can’t detect and correct knocking, leading to more severe issues, like an overheated engine, poor fuel economy, and misfires. 

If left unchecked, prolonged engine knocking can damage critical components such as pistons, connecting rods, and cylinder walls. It may also harm the catalytic converter or even escalate into a complete engine breakdown, leading to a hefty repair bill.

So, if you see a flashing check engine light on your dashboard, it’s crucial to contact an auto repair professional right away to prevent further damage.

How to Diagnose P0332

Diagnosing the P0332 code can be tricky as a DIY since many issues can cause it. For instance, without the right tools and knowledge, you might replace the knock sensor when the real problem is a faulty wire.

That’s why it’s best to have a mechanic diagnose and fix your vehicle.

They’ll do the following checks to diagnose the P0332 code:

1. Use an OBD2 scan tool to check if the knock sensor code P0332 or any other code is stored in the ECM.

2. Clear the existing fault codes and CEL. Then, they’ll test drive the car and inspect if the check engine light or P0332 code returns.

3. Perform a basic knock sensor test by monitoring the ignition timing with the help of the scan tool.

4. If the ignition timing is off, they’ll check the AC voltage readings from the knock sensor to ensure they’re within the specified range.

5. Check the AC voltage data from the temperature sensor, as false readings sent to the ECM can contribute to an engine knock.

6. If the check engine light is still illuminated, your mechanic will use the wiring diagram to inspect the knock sensor wire and harness for damages.

Possible repairs for P0332 & Costs

Based on the diagnosis of fault code P0332, your mechanic will do the following repairs:

1. Replace the damaged knock sensor wiring harness or connector
2. Ensure the sensor and circuit are grounded correctly and free from rust
3. Replace the bad knock sensor
4. Repair the faulty EGR or cooling system
5. Replace or reprogram the ECM or PCM (rare)

Repair cost:  

The cost of repairing the knock sensor code P0332 depends on the vehicle’s make, model, and location. It also depends on whether you choose aftermarket or original equipment manufacturer parts (OEM parts). Aftermarket sensors are often more affordable than OEM alternatives but may compromise quality.

Here are the average estimated replacement costs, including labor charges:

• Knock sensor harness or connector: $15 to $70
• EGR valve: $135 to $520
• Knock sensor: $285 to $400
• Temperature sensor: $400 to $500
• ECM: $800 and $1,500