Faulty crankshaft position sensor B (internal short or open circuit); Damaged or corroded sensor wiring harness or connector; Metal debris or damage on the sensor tip or reluctor wheel; Poor electrical connection at the ECM or sensor ground; Worn or damaged reluctor wheel teeth or incorrect air gap; ECM internal fault affecting the sensor input circuit

DTC codes / Nissan codes / P1337

P1337 · NissanCKP Sensor B Low Input

Q: What does code P1337 mean?

CKP Sensor B Low Input. P1337 on Nissan vehicles indicates that the engine control module has detected a low input signal from the crankshaft position sensor B circuit, which is typically the sensor responsible for monitoring the flywheel or flexplate. The ECM expects a fluctuating voltage as the reluctor wheel teeth pass the sensor, and a low input means the signal is below the expected threshold, which can disrupt ignition timing and fuel injection.

P1337 on Nissan vehicles indicates that the engine control module has detected a low input signal from the crankshaft position sensor B circuit, which is typically the sensor responsible for monitoring the flywheel or flexplate. The ECM expects a fluctuating voltage as the reluctor wheel teeth pass the sensor, and a low input means the signal is below the expected threshold, which can disrupt ignition timing and fuel injection.

SystemPowertrain

Code typeNissan specific

SeverityMedium

Fix difficultyIntermediate

AreaIgnition system and misfire

Symptoms you may notice

Illuminated check engine light, often with no other noticeable symptoms
Engine may crank but fail to start or start with difficulty
Rough running, misfiring, or stalling, especially at idle or low speeds
Reduced engine power or limp mode activation
Intermittent no-start condition that may temporarily resolve after sitting

Common causes, most likely first

Faulty crankshaft position sensor B (internal short or open circuit)
Damaged or corroded sensor wiring harness or connector
Metal debris or damage on the sensor tip or reluctor wheel
Poor electrical connection at the ECM or sensor ground
Worn or damaged reluctor wheel teeth or incorrect air gap
ECM internal fault affecting the sensor input circuit

How to diagnose and fix it

Inspect the sensor and connector for physical damage, corrosion, or debris, and clean or replace as needed
Check the sensor air gap and reluctor wheel condition using a feeler gauge and visual inspection
Measure sensor resistance and compare to Nissan specifications for the specific model and engine
Backprobe the sensor signal wire at the ECM and check for a low voltage signal while cranking
Perform a wiggle test on the wiring harness while monitoring sensor signal with a scan tool or oscilloscope
Check for continuity and short to ground on the sensor circuit between the sensor and ECM
If all electrical checks pass, replace the crankshaft position sensor B and clear the code

Crankshaft Sensor B Low Input Traps

A low input code often results from a poor ground connection at the sensor or ECM rather than a failed sensor, so always verify ground integrity before replacing parts.
Metal shavings or debris on the sensor tip can mimic a failed sensor by disrupting the magnetic field, and cleaning it may resolve the code without replacement.
Intermittent low input can be caused by a chafed wire that only shorts when the engine moves under load, so a wiggle test while cranking is essential.
Some Nissan models use a dual crankshaft sensor setup, and sensor B may be the one at the flywheel; misidentifying the sensor location leads to replacing the wrong part.
A weak battery or poor charging system can cause low sensor input voltage, so check battery voltage and grounds before condemning the sensor.

Can I keep driving with P1337?

If the engine starts and runs without stalling, you can drive cautiously to a repair shop, but avoid heavy acceleration or long trips because a failing crankshaft sensor can cause sudden stalling. If the engine will not start or stalls frequently, do not drive and have the vehicle towed to prevent safety hazards.

Tools that help

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