P0335 Code Explained: Crankshaft Position Sensor “A” Circuit Malfunction (Full Diagnostic Guide)

P0335 – Crankshaft Position Sensor “A” Circuit Malfunction

This code means the engine control module (ECM) is not receiving a proper signal from the crankshaft position sensor (CKP).

The crankshaft sensor is one of the most important sensors in the engine.

Without it, the engine often:

• will not start

• may stall unexpectedly

• may lose spark and injector pulse

🔬 What the Crankshaft Position Sensor Does

The CKP sensor monitors:

• crankshaft speed (RPM)

• crankshaft position

• piston movement timing

The ECM uses this information to control:

• ignition timing

• fuel injection timing

• misfire detection

If the crank signal disappears, the engine loses synchronization.

⚠ Why P0335 Is Serious

A failing crankshaft sensor can cause:

• sudden engine stall

• no-start condition

• intermittent shutdown

• misfire codes

• rough running

If the engine stalls at highway speed, it can be dangerous.

🔎 Most Common Causes of P0335

1️⃣ Failed Crankshaft Position Sensor (Very Common)

Heat and vibration cause internal failure.

Common pattern:

• works when cold

• fails when hot

• engine restarts after cooling

This “hot soak failure” is classic.

2️⃣ Damaged Wiring or Connector

Issues include:

• broken wires

• oil contamination

• loose connector

• corrosion

Intermittent wiring problems cause random stalling.

3️⃣ Faulty Camshaft Sensor (Related Timing Issue)

The ECM compares crank and cam signals.

If cam sensor signal is lost, P0335 may also appear.

👉P0340 Code Explained: Camshaft Position Sensor Circuit Malfunction (Full Diagnostic Guide)

4️⃣ Damaged Reluctor Ring (Tone Wheel)

The crank sensor reads a toothed ring on the crankshaft.

If the tone wheel:

• cracks

• loses teeth

• becomes misaligned

Signal becomes unstable.

Less common, but serious.

5️⃣ ECM Power or Ground Issues

Low battery voltage or poor grounds may trigger signal faults.

⚙️ Professional Diagnostic Workflow

Step 1: Check for Related Codes

Look for:

• P0340 (camshaft sensor)

• P0300 (misfire)

• P0016 (correlation)

Cluster analysis is critical.

Step 2: Monitor Live RPM While Cranking

If scanner shows:

• 0 RPM while cranking → crank sensor likely dead

• fluctuating unstable RPM → signal problem

No RPM = no crank signal.

Step 3: Inspect Sensor & Wiring

Check:

• metal debris on magnetic sensor tip

• connector damage

• proper sensor gap

Metal shavings can distort signal.

Step 4: Oscilloscope Test (Advanced)

Professional shops may test waveform pattern.

Irregular waveform confirms failure.

🚨 Symptoms of P0335

• engine cranks but won’t start

• sudden stall while driving

• hard starting

• rough idle

• loss of power

• intermittent engine shutdown

Sometimes the only symptom is Check Engine Light.

💰 Repair Costs

• Crankshaft sensor replacement: $150–400

• Wiring repair: $100–500

• Tone wheel repair: $800–2000+

• ECM replacement (rare): $800–1500

Most cases involve only the sensor.

❌ Common Misdiagnosis Mistakes

• Replacing cam sensor instead of crank

• Ignoring wiring

• Not checking RPM data

• Replacing starter or battery unnecessarily

• Clearing code without monitoring live data

📊 Quick Diagnostic Table

FAQ

Is P0335 serious?

Yes — it can cause stalling or no-start.

Can I drive with P0335?

Not recommended due to stall risk.

What is the most common fix?

Replacing the crankshaft position sensor.

How long does a crank sensor last?

Usually 80,000–150,000 miles.

Final Thoughts

P0335 indicates a crankshaft position sensor circuit issue — one of the most critical signals in the engine.

Correct diagnostic approach:

➡ Check live RPM data
➡ Inspect wiring
➡ Confirm signal stability
➡ Replace sensor if confirmed

Accurate diagnosis prevents unnecessary parts replacement.