Failed knock sensor 2 on bank 1, typically due to internal element degradation or heat damage; Damaged or corroded wiring harness between the knock sensor and the DME, including chafed insulation or broken strands; Loose or improperly torqued knock sensor mounting bolt, which prevents the sensor from picking up vibration correctly; Oil or coolant contamination at the sensor connector or mounting surface, which can attenuate the signal; Poor ground connection at the sensor or engine block, causing a low reference voltage; Faulty DME internal knock detection circuit, though this is far less common than sensor or wiring issues; Aftermarket or incorrect knock sensor installed previously that does not match BMW specifications

DTC codes / BMW codes / P1327

P1327 · BMWKnock Sensor 2 Bank 1 Low Input

Q: What does code P1327 mean?

Knock Sensor 2 Bank 1 Low Input. P1327 on a BMW means the engine control module (DME) is seeing an abnormally low voltage signal from knock sensor 2 on bank 1, which is the sensor monitoring cylinders 1 through 3 on the bank that contains cylinder 1. The DME compares this signal against expected values and flags the code when the input stays below the acceptable threshold, which prevents reliable detection of detonation and forces the module to pull timing as a protective measure.

P1327 on a BMW means the engine control module (DME) is seeing an abnormally low voltage signal from knock sensor 2 on bank 1, which is the sensor monitoring cylinders 1 through 3 on the bank that contains cylinder 1. The DME compares this signal against expected values and flags the code when the input stays below the acceptable threshold, which prevents reliable detection of detonation and forces the module to pull timing as a protective measure.

SystemPowertrain

Code typeBMW specific

SeverityMedium

Fix difficultyIntermediate

AreaIgnition system and misfire

Symptoms you may notice

Illumination of the check engine light, often with no other symptoms noticed by the driver
Reduced engine power or sluggish acceleration as the DME retards ignition timing to protect against undetected knock
Rough running or hesitation under load, particularly during acceleration or climbing hills
A slight decrease in fuel economy because the engine is no longer operating at optimal spark advance
In some cases, a faint knocking or pinging sound if the fault masks real detonation that the DME cannot hear
Intermittent misfire-like behavior on cylinders 1 through 3 when the sensor signal drops out under vibration

Common causes, most likely first

Failed knock sensor 2 on bank 1, typically due to internal element degradation or heat damage
Damaged or corroded wiring harness between the knock sensor and the DME, including chafed insulation or broken strands
Loose or improperly torqued knock sensor mounting bolt, which prevents the sensor from picking up vibration correctly
Oil or coolant contamination at the sensor connector or mounting surface, which can attenuate the signal
Poor ground connection at the sensor or engine block, causing a low reference voltage
Faulty DME internal knock detection circuit, though this is far less common than sensor or wiring issues
Aftermarket or incorrect knock sensor installed previously that does not match BMW specifications

How to diagnose and fix it

Read and record all stored and pending fault codes with a BMW-capable scan tool, then clear codes and test drive to confirm P1327 returns
Visually inspect knock sensor 2 on bank 1 for a secure mounting bolt, clean mating surface, and intact connector
Check the sensor wiring harness for chafing, corrosion, or loose pins between the sensor and the DME, repairing as needed
Measure the knock sensor resistance and compare it to BMW specifications for the engine, replacing the sensor if out of range
Verify the sensor mounting bolt torque with a calibrated torque wrench, as incorrect torque alters the vibration signal
Perform a wiggle test on the harness while monitoring knock sensor live data to catch intermittent wiring faults
If all external checks pass, test the DME knock input circuit or substitute a known-good DME to rule out an internal module fault

What BMW technicians check before replacing sensors

A loose knock sensor bolt is one of the most common causes of P1327 on BMW engines, and simply re-torquing to specification often resolves the code without any new parts.
Oil leaks from the valve cover gasket frequently contaminate the knock sensor connector on bank 1, so always inspect for oil residue before condemning the sensor itself.
The DME may set P1327 as a consequence of a failing ground strap between the engine and chassis, which raises the reference voltage and makes the sensor signal appear low.
Aftermarket knock sensors for BMW engines often have different piezo element characteristics and can trigger P1327 even when new, so genuine or OEM-equivalent parts are strongly preferred.
P1327 does not always mean the sensor is dead; a shorted signal wire to ground or a damaged shield in the harness will produce the same low input reading and must be ruled out first.

Can I keep driving with P1327?

You can drive the vehicle short distances to a repair shop, but avoid heavy acceleration, towing, or sustained high-load driving because the DME cannot reliably detect knock and may not protect the engine from detonation. Prolonged driving with this fault risks engine damage if real knock occurs undetected.

Tools that help

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Guidance is general and written for BMW vehicles. Exact tests and values vary by model, so confirm the fault before replacing parts.