P0332 Code: Knock Sensor 2 Low Input — Causes & How to Fix

P0332 means the engine computer is reading a signal from knock sensor 2 that is lower than a working sensor circuit should produce. It does not mean the engine is knocking. It means the computer has stopped trusting one of the sensors that listen for knock, so it usually pulls ignition timing back as a precaution, and the car feels slightly flat and uses a little more fuel. Two things decide what to do next. The first is which physical sensor is “sensor 2” on your engine, because that is not the same on every engine and it is often the one buried under the intake manifold. The second is whether P0332 is stored alone or alongside P0327, the same fault on sensor 1, because the two patterns point at different repairs. This article covers what sets P0332, its six real causes in order of likelihood, the order to test them in, and what each repair typically costs.

Start with the table, then read the triage note under it.

Cause	Telltale Sign	Typical Cost
Damaged wiring or a shared connector	P0332 and P0327 together; chafed, heat-hardened or oil-soaked harness	$50 to $600
Moisture in the sensor or its connector	Code sets on cold or damp starts and does not return once warm	$0 to $150
Failed knock sensor 2	P0332 alone; wiring tests good but the sensor gives no signal	$150 to $900 installed
Loose or wrongly torqued sensor	Code appeared after work near the sensor	$0 to $600
Sensor or harness disturbed during repair	Code appeared straight after intake, head or timing work	$0 to $600
Engine computer or software	Sensor and wiring test good; a bulletin covers your engine	$0 to $1,000

Stop driving hard, and stop entirely, if you can hear the engine pinging, rattling or knocking under acceleration. With one knock sensor out of the picture, the computer may not catch real detonation on the cylinders that sensor covers, and sustained knock can damage pistons. Most engines protect themselves by retarding timing while P0332 is set, so the usual result is a car that is a little slower but runs smoothly. That is safe to drive gently to a diagnosis. Use the fuel grade your owner’s manual specifies, and avoid towing and full-throttle driving until it is fixed.

What P0332 Actually Means

A knock sensor is a small piezoelectric microphone bolted to the engine block or cylinder head. When fuel ignites too early in a cylinder, the block rings at a characteristic frequency, and the sensor turns that vibration into a small AC voltage. The engine computer listens to it and retards ignition timing on the affected cylinders until the knock stops. That lets the engine run as much timing advance as the fuel and conditions allow, which is where its power and economy come from.

P0332 is the generic definition “knock sensor 2 circuit low”. The computer watches each sensor’s circuit as well as its signal, and sets P0332 when the signal or circuit voltage for sensor 2 stays below the level an intact, working sensor produces. It is an electrical code about the sensor and its wiring. On its own it says nothing about whether the engine is actually knocking, and a knocking engine with healthy sensors will not set it.

The codes for knock sensor 2 run in a parallel set to sensor 1: P0330 is the general circuit fault, P0331 range or performance, P0332 circuit low and P0333 circuit high. The sensor 1 equivalents are P0325 to P0328.

Which Sensor Is “Sensor 2”?

This is the first point that saves money, because the two sensors on a V engine are rarely equally easy to reach, and replacing the wrong one is an expensive way to learn the numbering.

On most V6 and V8 engines with two knock sensors, and on horizontally opposed engines such as Subaru’s, sensor 2 is the one on Bank 2, the side of the engine that does not contain cylinder 1. On many V engines both sensors sit in the valley under the intake manifold, so “Bank 2” does not mean “the easy side”. Engines with more than two sensors number them differently again. Maserati’s diagnostic sheet DS 25-26 for its Quattroporte, Ghibli and Levante lists P0327 “Knock Sensor 1 Circuit Low” and P0332 “Knock Sensor 2 Circuit Low” on both the V6 and the V8, and adds P032C and P033C for knock sensors 3 and 4, which apply only to the V8. On that V8, sensor 2 is one of four sensors, not “the Bank 2 sensor”.

So before buying anything, look up the knock sensor location for your exact engine in the service information, or ask a dealer parts counter to identify the sensor by position. Then trace the harness from the sensor you think is sensor 2 to its connector and confirm it is the circuit that goes to the computer pins for sensor 2.

P0332 Alone or With P0327?

The second point, and the one the whole diagnosis turns on. Two knock sensors almost never fail at the same moment. When both circuits drop low together, the cause is nearly always something they share: a common connector, a single sub-harness that carries both sensors, a shared shield or ground, or the computer itself.

Ford’s technical service bulletin 18-2367 is a clear example. It covers 2016 and 2017 Explorer and Police Interceptor Utility vehicles with the 3.5L EcoBoost built on or before 30 September 2016 that show “DTCs P0325, P0327, P0330 and/or P0332”. The cause it gives is “a wire chafe condition near the knock sensor connector C109”. The repair is to splice the damaged wiring and sleeve the harness in convoluted tubing, not to replace either sensor. The bulletin also only applies when those knock sensor codes are the only ones stored, which is a useful discipline in general: deal with any other stored codes first.

• P0332 alone points at sensor 2’s own circuit: its sensor, its connector, its branch of the harness or its mounting.
• P0332 with P0327 (or P0330 with P0325) points at what the two share. Inspect the common connector and harness before touching either sensor.
• P0332 with misfire codes or lean codes means a separate problem is running alongside. Severe mechanical noise or misfires can confuse knock detection, so fix those first and see whether P0332 returns.

Freeze frame data, stored with the code, adds a third clue. It records engine temperature, speed and load at the moment P0332 set. A code that set on a cold, damp start and has not returned once the engine was warm points toward moisture. One that sets hot or under load, or comes straight back after clearing, points toward wiring or the sensor.

Symptoms You May Notice Alongside the Code

Often nothing beyond the check engine light. When the computer does retard timing as a precaution, you may notice slightly reduced power, sluggish acceleration up hills or when loaded, and lower fuel economy. On a scan tool, the timing advance reading will often be lower than normal for the engine speed and load. P0332 should not make the engine knock. If you hear pinging or rattling under acceleration, treat that as a separate and more urgent problem. The site’s guide to engine knocking when accelerating covers the causes of real knock, and how to identify rod knock covers the mechanical kind that no sensor can fix.

1. Damaged Wiring or a Shared Connector

Knock sensor wiring carries a small signal, is usually shielded, and often runs under the intake manifold or close to hot exhaust parts. Heat hardens and cracks the insulation, oil and coolant leaks soak into it, and a harness that rubs against a bracket or a coolant outlet eventually wears through, which is exactly the Ford condition above. A chafed signal wire, a damaged shield, or a connector with spread or corroded terminals can pull the signal low.

This is the most likely cause when P0327 is stored too, and still a strong candidate when P0332 is alone. With the sensor and computer disconnected, check each sensor 2 wire for continuity end to end, and for shorts to ground and to the other wires. Flex the harness at clips and brackets while watching the reading, because a chafe often only opens or shorts when the engine moves.

2. Moisture in the Sensor or Its Connector

Water in a knock sensor or its connector can drag the signal low. Sensors in an engine valley can sit in water that collects from a leaking cowl, a washed engine bay, or coolant seeping from a leaking intake or thermostat housing above them. The Maserati sheet describes exactly this, stating that P0327, P0332, P032C and P033C “may be triggered in cold or humid conditions due to condensation affecting knock sensor operation”. Its fix is a controlled warm-up procedure to burn the moisture off, performed before any parts are replaced. The procedure reads the engine temperature at which the code set from the freeze frame, clears the code, holds the engine at 3,000 rpm in Park until it reaches at least that temperature without exceeding 110 °C, then lets it idle until the cooling fan stops and rechecks.

That procedure is specific to those vehicles, but the principle travels. If the code only appears on cold, damp mornings, dry and inspect the connector, find out where the water is coming from, and see whether the code returns before replacing anything.

3. Failed Knock Sensor 2

Knock sensors can crack internally or lose output with heat and age. A failed sensor is the most likely cause when P0332 sets alone, the wiring has tested good, and the code returns whatever the conditions. Manufacturers do revise these parts. Subaru’s service bulletin 07-133-18 for the 2015 to 2017 WRX and 2014 to 2017 Forester Turbo announced a redesigned knock sensor to “increase durability”, noting that a knock sensor DTC, P0327, P0328, P0332 or P0333, may have set.

To test the sensor, follow the service information for your engine. Some sensors have a specified resistance, while some piezo types read open circuit on a meter, so a “no reading” result is not automatically a failure. The most convincing test is an oscilloscope on the signal: tapping the block lightly near the sensor with a small wrench should produce a clear burst of signal. No signal with proven wiring condemns the sensor.

4. Loose or Wrongly Torqued Sensor

A knock sensor hears the engine through its mounting, so the contact between sensor and block matters. A sensor that has worked loose, sits on a dirty, painted or corroded face, or was overtightened and cracked will not pass vibration correctly. Manufacturers specify an exact tightening torque for this reason, and some forbid additives on the threads. Subaru’s bulletin gives 24 Nm (17.7 ft-lb) for the retaining bolt and states, “Do NOT use anti-seize compound on the sensor retaining bolt threads.” If the code appeared after work near the sensor, check that it is clean, seated flat and torqued to the figure for your engine.

5. Sensor or Harness Disturbed During Repair

Intake manifold, cylinder head, timing chain and water pump jobs all happen next to the knock sensors and their sub-harness. A connector left unplugged or not fully latched, a harness trapped under the manifold, or a sensor knocked during the work can set P0332 on the first drive afterwards. If the code started immediately after such a repair, look there first, and expect to remove the same parts again to reach it.

6. Engine Computer or Software

Knock detection thresholds live in the engine software, and manufacturers occasionally revise them. If the sensor and wiring test good and P0332 keeps returning without a clear pattern, ask a dealer to check for service bulletins and software updates for your engine. A failed knock input inside the computer is possible but rare, and should be the last conclusion rather than the first.

Diagnostic Order

1. Listen for real knock under load. If you hear it, deal with that first.
2. Record every stored code and the freeze frame data. Note whether P0327 or P0325 is also stored, and the engine temperature when P0332 set.
3. Identify which physical sensor is sensor 2 on your engine, from the service information, before buying any parts.
4. Check for service bulletins for your engine, especially for harness chafe or sensor revisions.
5. Inspect the accessible harness and connectors for chafing, oil or coolant contamination, moisture and loose terminals. If both sensors are coded, start at the part of the harness they share.
6. Clear the code and note when it returns: only on cold, damp starts points to moisture; immediately or under load points to wiring or the sensor.
7. Test the sensor 2 circuit for continuity and shorts with the sensor and computer disconnected.
8. Test the sensor itself, and replace it, torqued to specification, only once the tests point at it.

What not to do: do not replace both knock sensors because both codes are stored without first checking the shared harness, and do not replace the more accessible sensor on the assumption that it is sensor 2.

Repair Cost

Typical costs, labelled as typical because access varies enormously from one engine to another:

• Drying or cleaning a connector, or a terminal repair: nothing to about $150.
• Wiring splice and sleeving where the harness has chafed: roughly $50 to $300, more if coolant or the intake has to come off for access.
• Knock sensor on an accessible engine, where it bolts to the side of the block: roughly $150 to $350 installed.
• Knock sensor under the intake manifold, common on V6 and V8 engines: roughly $400 to $900 installed, most of it labour.
• Knock sensor sub-harness: roughly $100 to $600, often done at the same time as the sensors.
• Software update: often free under a bulletin or warranty, otherwise up to about $200.

Where both sensors sit under the intake manifold and sensor 2 has been proven faulty, many owners choose to replace both sensors and the sub-harness while the manifold is off, because the labour to get there is the bulk of the bill. That is a reasonable decision once a fault is proven. It is not a substitute for testing first.

Can You Keep Driving With a P0332 Code?

Gently, yes, for a short time. Most engines respond to P0332 by retarding ignition timing, which trades some power and economy for safety, and the car remains driveable. The risk is that while sensor 2 cannot be trusted, genuine knock from low-octane fuel, overheating, carbon build-up or heavy load may go undetected on the cylinders it covers. Use the correct fuel, avoid towing and hard acceleration, and stop if you hear pinging. Turbocharged engines run higher cylinder pressures and are less forgiving of undetected knock, so treat P0332 on a turbo engine with more urgency.

If the code is only setting on cold, damp mornings and the car drives normally, it is low urgency. It will still keep the check engine light on, which hides any new fault that comes along, and it can fail an emissions inspection.

Related Codes

• P0327: knock sensor 1 circuit low, the same fault on the other sensor, usually Bank 1. Together with P0332 it points at shared wiring. See the P0327 guide.
• P0325: knock sensor 1 circuit malfunction, the general version of the sensor 1 fault. See the P0325 guide.
• P0330: knock sensor 2 circuit malfunction, the general version of the fault P0332 describes.
• P0331: knock sensor 2 range or performance. The signal is electrically present but implausible.
• P0333: knock sensor 2 circuit high, the opposite of P0332, often an open circuit or a short to voltage.
• Misfire codes (P0300 to P0308): a separate problem. Misfires are not knock, although a misfiring or mechanically noisy engine can upset knock detection. See the P0300 guide.

For a broader look at knock sensor failure and how to test one, see the site’s guide to knock sensor failure symptoms and testing, and for knocking noises in general, engine knocking sounds and their causes.

Frequently Asked Questions

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