P0337 — Crankshaft Position Sensor “A” Circuit Low #

Note: The wording of this code may vary slightly depending on the vehicle manufacturer.

• Crankshaft Position Sensor “A” Circuit Low Input (Generic, Ford, GM, Honda, Toyota, Nissan, Hyundai)
• Crank Position Sensor A Circuit Low Input (Chrysler, Dodge, Jeep)
• Engine Speed Sensor ‘A’ Low Input (Volkswagen Group)
• CKP Sensor “A” Circuit Low (Mazda, Kia)

Overview of Code P0337 #

P0337 is a diagnostic trouble code (DTC) that indicates the Engine Control Module (ECM) or Powertrain Control Module (PCM) has detected a low voltage signal from the Crankshaft Position Sensor “A” circuit. This sensor plays a pivotal role by letting the ECM/PCM know the exact position and rotational speed of the crankshaft—a critical parameter for precise fuel injection and ignition timing. When the circuit voltage falls below the expected threshold, the engine may run poorly or not at all. This code is common across many makes and models, but the underlying cause and repair steps are often similar. If left unaddressed, it can lead to severe drivability issues or even prevent the engine from starting.

Common Symptoms for Code P0337 #

When P0337 is triggered, drivers may notice a range of performance issues. The severity of symptoms depends on whether the sensor is intermittently failing, completely failed, or if there’s a wiring problem. Common signs include:

• Engine cranks but does not start
• Hard starting or repeated stalling
• Rough or erratic idle
• Reduced engine power or hesitation during acceleration
• Illuminated Check Engine Light (CEL)
• Poor fuel economy
• Possible misfire codes stored in addition to P0337

Most Likely Causes for Code P0337 #

The P0337 code is most often triggered by issues in the crankshaft position sensor circuit. This can stem from the sensor itself, its wiring, or related engine components. Here are the most frequent causes, ordered by likelihood:

1. Faulty crankshaft position sensor (CKP sensor)
2. Damaged, corroded, or loose sensor connector
3. Broken, frayed, or shorted wiring in the CKP sensor circuit
4. Debris or metal shavings on the sensor tip (especially if magnetic type)
5. Failed or weak battery/charging system causing low reference voltage
6. Damaged reluctor ring (the toothed wheel on the crankshaft)
7. Aftermarket engine modifications affecting sensor signal
8. Faulty ECM/PCM (rare, but possible)

Step-By-Step Diagnostic for P0337 #

Proper diagnosis is the key to fixing P0337 efficiently. Here’s a recommended step-by-step approach a technician or skilled DIYer should follow:

1. Use an OBD-II scanner to confirm the presence of P0337 and check for related codes.
2. Visually inspect the crankshaft position sensor and its wiring harness for obvious damage, loose connections, or corrosion.
3. Check the sensor connector for bent pins, water intrusion, or poor fit.
4. Test the CKP sensor’s resistance and output signal with a digital multimeter (refer to OEM specifications).
5. Inspect the sensor mounting area for debris or metallic shavings and clean as needed.
6. Check battery voltage and charging system operation to rule out low system voltage.
7. If accessible, inspect the reluctor ring for missing teeth or damage.
8. If all checks pass, use an oscilloscope (if available) to observe the CKP sensor waveform while cranking/running.
9. As a last step, consider ECM/PCM testing or replacement if no other faults are found.

Possible Repairs for Code P0337 #

Once the root cause is identified, repairs for P0337 typically involve addressing the sensor circuit. Typical solutions include:

• Replace the faulty crankshaft position sensor
• Repair or replace damaged wiring or connectors in the sensor circuit
• Clean the sensor tip and mating surface of debris or metallic buildup
• Repair or replace a damaged reluctor ring
• Ensure all connections are tight and corrosion-free
• Replace or recharge a weak battery and/or repair charging system faults
• Reprogram or replace the ECM/PCM (very rare, only if all else fails)

Is It Safe to Drive with Code P0337? #

Driving with code P0337 is NOT recommended. In many cases, the engine may not start at all, or it could stall unexpectedly while driving—posing a safety risk. If the engine does run, performance will be seriously compromised, leading to rough running, hesitation, or even further damage. Address this issue as soon as possible to avoid being stranded or causing additional engine problems.

Vehicles Most Commonly Affected by P0337 #

While P0337 can appear in virtually any OBD-II compliant vehicle, some makes and models see this code more often due to sensor placement or wiring design. These include:

• Chevrolet Silverado, Malibu, and Cruze
• Honda Accord and Civic
• Toyota Camry and Corolla
• Nissan Altima and Sentra
• Hyundai Elantra and Sonata
• Ford Focus and F-150
• Chrysler 300, Dodge Ram, and Jeep Grand Cherokee
• Volkswagen Jetta and Passat

Frequent Mistakes & Best Practices for P0337 #

Misdiagnosing P0337 can lead to unnecessary part replacements and wasted time. Avoid these common pitfalls and stick to proven practices:

• Replacing the sensor without testing the wiring or connector
• Ignoring corrosion or loose connections at the sensor plug
• Not checking for debris or metal shavings on the sensor tip
• Overlooking battery and charging system voltage
• Neglecting to inspect the reluctor ring for physical damage

• Always check OEM repair manuals for specific test values and procedures
• Use a scan tool with live data to monitor CKP sensor readings
• Clear codes after repairs and confirm the fault does not return

Express FAQ for Code P0337 #

Q: Can a bad crankshaft position sensor cause my engine to not start at all?
A: Yes. If the sensor signal is missing or too low for the ECM/PCM to recognize, the engine may crank but never start because it cannot determine proper spark and fuel timing.

Q: Is it expensive to fix P0337?
A: Repair costs vary. A new CKP sensor and labor usually cost less than $250 at most shops, but if wiring or ECM/PCM replacement is needed, expenses can rise. Always diagnose before replacing parts.