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P0337: Crankshaft Position (CKP) Sensor: Circuit Low Input

Severe

Quick answer

P0337 means the crank sensor’s signal is stuck low, typically a short to ground, an open signal wire, or a dead sensor. When this signal drops, the engine simply stops: stalling (often when hot), long cranks, or a no-start with no spark and no injector pulse. Intermittent failures famously strand people and then start fine for the tow truck. Check the connector and wiring before buying a sensor: for this variant of the code, wiring is the most common answer.

What it means

The crankshaft position (ckp) sensor tells the engine computer the exact rotational position and speed of the crankshaft: the master timing signal every spark and injection event is scheduled from. P0337 sets when the signal is stuck low, typically a short to ground, an open signal wire, or a dead sensor for long enough that the computer stops trusting it.

Circuit codes describe electrical behavior, which puts the wiring, the connector, and the sensor on equal footing as suspects. The cheapest of the three fails most often.

Because the crank signal is a primary timing input, losing it can stop spark and injection. Some vehicles may keep running briefly using other signals, but a stall or no-start is common.

P0337 symptoms: what you'll notice

  • The engine stalls without warning, often once it’s fully warmed up or in stop-and-go traffic.
  • It cranks but won’t start, or takes far longer than normal to fire.
  • It dies when hot, then restarts fine after sitting and cooling down.
  • The tachometer drops to zero or twitches while the engine is running.
  • Sudden cutting out or bucking at speed, as if the key were flicked off for an instant.

Common causes

Ordered from most to least likely.

  1. 1.

    Wiring damage (chafe, break, melted insulation)

    A short to ground pins the signal low.

  2. 2.

    Corroded, loose, or backed-out connector pins

    Unplug and inspect both halves under good light.

  3. 3.

    Failed crank sensor

    Confirm with measurements before replacing.

  4. 4.

    Heat-related sensor failure

    The classic pattern: stalls when fully warm, restarts after cooling down.

  5. 5.

    Lost 5V reference or sensor ground (where applicable)

    If several sensors fault together, suspect a shared reference circuit rather than coincidence.

How to fix it: diagnosis, step by step

Cheapest and most likely checks first.

  1. 1 Read the freeze frame

    Note when P0337 sets: cold start, warm idle, under load, over bumps. The conditions narrow the cause dramatically, especially for intermittent faults.

  2. 2 Inspect connector and harness

    Unplug the sensor; check for corrosion, bent or spread pins, and chafed insulation along the harness run. Re-seat firmly. This free step resolves a remarkable share of circuit codes.

  3. 3 Watch it in live data

    During cranking, RPM should register on the scanner (~150–250 RPM). Cranking with zero RPM displayed is the textbook dead-CKP signature.

  4. 4 Inspect the sensor tip and reluctor

    Pull the sensor and look: metal shavings stuck to the magnetic tip, oil intrusion in the connector, or a damaged tone-ring tooth all produce these codes. Check the air gap where adjustable.

  5. 5 Wiggle-test if intermittent

    Engine running, data live: gently flex the harness and tap the sensor while watching the reading. A glitch you can provoke is a fault you can find.

  6. 6 Replace with a quality part

    If measurements condemn the sensor, buy OEM or a reputable brand: bargain sensors re-set these codes often enough to cost more in time than they save in money.

Known P0337 patterns by make

Brand-specific failure patterns from the field: find your make before parts-shopping.

Jeep 1991–2004 4.0L (Cherokee, Grand Cherokee, Wrangler)

The 4.0L inline six is the textbook hot-stall crank sensor: the engine dies fully warmed up, restarts after cooling down, and repeats that routine for weeks before failing outright. The sensor bolts to the bellhousing and the part is cheap, which is why seasoned owners carry a spare.

Nissan 2004–2006 Altima, Maxima, Quest 3.5L V6

These V6s had factory campaigns replacing crank and cam position sensors for exactly this stalling pattern. Before paying for a sensor, have a dealer run the VIN for open campaigns; the repair may be free even years later.

Chrysler/Dodge 3.3L/3.8L minivans (Caravan, Town & Country, Voyager)

A classic intermittent no-start: the van cranks with no spark and no tachometer movement, then starts an hour later like nothing happened. A failing sensor here often leaves no code at first, so a stored P0337 is a gift. The part is inexpensive and access is reasonable.

Parts & tools you may need

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Frequently asked questions

What does code P0337 mean?
P0337 means the crank sensor’s signal is stuck low, typically a short to ground, an open signal wire, or a dead sensor. It’s serious: diagnose it promptly to avoid expensive damage.
Can I drive with P0337?
Risky. An engine that can cut out without warning is a safety problem in traffic: diagnose promptly, and avoid critical trips until fixed.
Is it the sensor or the wiring?
For this variant, lean wiring: stuck-low, stuck-high, and intermittent signatures are circuit behaviors. Inspect and measure before buying the sensor.
Why did the code return after a new sensor?
Because the circuit, not the sensor, was the fault, or the replacement was low quality. Re-do the wiring inspection the first repair skipped.
What happens when the crank signal disappears?
The computer may lose the timing reference needed for spark and injection, causing a stall or no-start. Behavior varies by engine strategy.
How much does a crankshaft position sensor cost to replace?
The sensor itself usually runs $20 to $100 for a quality brand. Labor is where the range opens up: many sit near the crank pulley or bellhousing and take under an hour, while a few hide behind engine mounts or intake hardware and push the job past two hours. When the real fault is wiring, the repair is usually cheaper than the sensor.
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