What causes knock sensor low input?

The Check Engine Light flickering on your dashboard is the first noticeable symptom for any engine code, including DTC P0327 and P0332 (both knock sensor error codes.)

However, you’ll need an OBD2 scan tool to help determine the exact cause of the lit Check Engine Light on your dashboard. 

2. A Pinging Or Knocking Sound

If you have code P0332, the output signal from the knock sensor is too low to signal the ECM when your engine produces a pinging or knocking sound.

As such, the ECM doesn’t retard the ignition timing when the air-fuel combusts early, resulting in unresolved engine knocking while accelerating or idling.

3. Sudden Loss Of Engine Power

Your engine losing power is another common sign of a malfunctioning knock sensor or code P0332.

A faulty knock sensor may fail to report when the ignition timing is off, resulting in the spark plug igniting the air-fuel mixture late.

Due to this delay in combustion, the engine cannot fully burn the air and fuel mixture, resulting in your engine losing power.

4. An Overheated Engine

An overheated engine could result 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 get a mechanic to diagnose the issue and see if it’s due to the diagnostic trouble code P0332.

5. Increased NOx Emissions

An engine problem related to the “Knock Sensor 2 Circuit Low Input” error could damage your vehicle’s catalytic converter.

With a damaged catalytic converter, your engine cannot convert toxic pollutants into less harmful emissions, resulting in your vehicle failing the emissions test.

In some cases, increased NOx emissions could be due to a negative fuel trim caused by a bad O2 sensor. 

6. Decreased Fuel Efficiency

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

While a drop in fuel efficiency could be due to fault DTC P0332, there are many other potential reasons, so you should get your vehicle checked soon.

This diagnostic trouble code (DTC) is a generic powertrain code, which means that it applies to OBD-II equipped vehicles. Although generic, the specific repair steps may vary depending on make/model.

A knock sensor tells the engine computer when one or more of your engine's cylinders are "knocking", that is, exploding the air/fuel mixture in a way that delivers less power and can be damaging to the engine if prolonged.

The computer uses this information to tune the engine so that it doesn't knock. If your knock sensor on Bank #1 is generating a low output voltage (perhaps under 0.5V), then it will trigger a P0327 DTC. This P0327 code may show up intermittently or the Service Engine light may be lit constantly. Other knock sensor related DTC codes include P0325, P0326, P0328, P0329, P0330, P0331, P0332, P0333, and P0334.

Symptoms

You may notice drivability problems including fluctation engine RPM, a loss of power, and perhaps some hesitation. There may also be other symptoms.

Causes

Potential causes for a P0327 DTC include (but are not limited to):

• The knock sensor is faulty and needs to be replaced
• There is a wiring open/short/fault in the knock sensor circuit
• The PCM/ECM has failed

Possible Solutions

• Verify the resistance of the knock sensor (compare it to factory specs)
• Inspect for broken/frayed wires leading to the sensor
• Check the wiring and connections leading to/from the knock sensor and PCM/ECM
• Verify proper voltage is reaching the knock sensor (e.g. 5 volts)
• Verify proper grounding of sensor and circuit
• Replace the knock sensor
• Replace the PCM/ECM

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