P0335 Code — Crankshaft Position Sensor A Circuit Malfunction (Causes & How to Fix)

Quick Check – 60‑Second Diagnosis

A flashing check‑engine light paired with a rough idle is often the first clue. With a P0335 code, you can perform a rapid sanity check before pulling out tools:

1. Turn the key to “ON” (engine off). Listen for a faint “click” from the CKP sensor—many sensors generate a small audible pulse when powered.
2. Look at the OBD‑II scanner for any additional codes such as P0325 (CKP sensor B circuit) or P0306 (cylinder‑6 misfire). Multiple codes may point to a wiring harness problem rather than a single sensor.
3. Visually inspect the connector for loose pins or obvious corrosion. If the plug wiggles or the pins are bent, tighten or clean it and clear the code. If the light stays on, move on to the full diagnosis.

Safety Note: Always disconnect the negative battery terminal before removing the sensor to avoid accidental short circuits or shocking the ECM.

Symptoms You’ll Notice While Driving

Understanding the real‑world impact of a bad crankshaft position sensor helps you decide how urgently to act.

If you experience any of the above, especially a stall while driving, it’s safest to pull over and have the vehicle inspected before you continue.

Root Causes – What Triggers This Code

While the sensor itself is a frequent culprit, the underlying reasons span several systems.

1. Faulty Crankshaft Position Sensor A

The sensor’s Hall‑effect or magnetic pickup can wear out, especially on high‑mileage engines (>100 k miles). Heat soak from the exhaust can also degrade the internal electronics.

2. Wiring Harness Damage

The sensor’s signal wire runs close to the engine block, the exhaust manifold, and the timing cover. Scrapes, oil leaks, or heat‑induced brittleness can cause intermittent shorts or opens.

3. Bad Connector or Corrosion

Moisture intrusion, especially in climates with heavy rain or road salt, creates corrosion on the connector pins, leading to a poor electrical path.

4. Timing‑Chain or Timing‑Belt Issues

If the mechanical timing is off (e.g., a stretched chain), the sensor will generate a signal that doesn’t match the actual crank position, prompting the ECM to flag a fault.

5. ECM Power or Ground Problems

A weak ground strap or a failing ECM power supply can make the CKP circuit appear “malfunctioning” even when the sensor is healthy.

Step‑by‑Step Diagnosis & Repair

Below is a logical progression from the simplest visual checks to the more involved sensor replacement. Follow the order; each step builds on the previous one.

Step 1 – Visual Inspection – Loose Connections & Damaged Wiring

What to do:

• Open the hood and locate the CKP sensor (usually on the engine block near the crank pulley).
• Disconnect the electrical connector. Look for bent pins, corrosion, or broken plastic clips.
• Trace the wiring harness for any cracks, chafed sections, or oil stains.

Good vs. Bad:

• Good: Connector seats firmly, pins are straight, harness is intact.
• Bad: Loose pins, visible corrosion, or exposed wires.

Tools: Flashlight, 10 mm socket (to remove any retaining bolts), wire brush (to clean corrosion).

Why it matters: A loose connector can produce the exact “circuit malfunction” the ECM reports. Fixing this alone may clear the code.

Step 2 – Check for Faulty Sensor Power Supply

What to do:

1. Re‑connect the sensor plug.
2. Turn the ignition to the “ON” position (engine still off).
3. Using a digital multimeter set to DC volts, probe the sensor’s power wire (usually a pink or red wire).
4. Verify that you see the voltage specified by the service manual (typically battery voltage, ~12 V, when the key is on).

Good vs. Bad:

• Good: Voltage present and stable at the specified level.
• Bad: No voltage, or voltage drops dramatically when the engine is cranked.

Tools: Digital multimeter, OBD‑II scanner (to confirm the code is still present after this test).

Why it matters: No power means the ECM can’t read the sensor, resulting in a P0335 regardless of sensor condition.

Step 3 – Read Live Data – Crankshaft Position Signal

What to do:

• Plug an OBD‑II scan tool into the vehicle’s data link connector.
• Navigate to “Live Data” → “Crankshaft Position Sensor A” (often displayed as “CKP A” or “Engine RPM”).
• Have an assistant crank the engine while you watch the graph.

Good vs. Bad:

• Good: A smooth, steady waveform that rises proportionally with engine speed.
• Bad: Flat line (no signal) or erratic spikes (intermittent signal).

Tools: OBD‑II scanner capable of live data (e.g., Autel MaxiCOM, BlueDriver).

Why it matters: This step tells you whether the sensor is actually sending data to the ECM. A missing signal points to sensor or wiring failure.

Step 4 – Test Sensor Resistance

What to do:

1. With the engine off, disconnect the sensor connector again.
2. Set the multimeter to the ohms (Ω) range.
3. Measure resistance between the signal terminal and ground.
4. Compare the reading to the range listed in the repair manual (often a few hundred ohms for Hall‑effect sensors).

Good vs. Bad:

• Good: Resistance falls within the manufacturer’s specified window.
• Bad: Open circuit (∞ Ω) or resistance far outside the spec.

Tools: Digital multimeter, 10 mm socket (to remove sensor if needed).

Why it matters: Even if the wiring looks fine, an internally failed sensor will show abnormal resistance.

Step 5 – Replace Crankshaft Position Sensor A

When to replace:

• Resistance test fails, or
• Live data shows no signal despite proper voltage, or
• Visual inspection reveals physical damage to the sensor housing.

What to do:

1. Disconnect the negative battery terminal (minimum 10 seconds).
2. Remove any bolts or brackets holding the sensor (usually one 10 mm bolt).
3. Pull the sensor out gently; some models have a rubber boot that may need a slight twist.
4. Install the new sensor, torque the mounting bolt to the specification (commonly 8–12 Nm).
5. Re‑connect the electrical plug, re‑attach the battery, and clear the code with the scanner.
6. Start the engine and watch live data to confirm a clean, steady CKP signal.

Good vs. Bad:

• Good: Sensor is securely mounted, torque is correct, and the live data shows a clean waveform.
• Bad: Sensor wobbles, bolt is under‑torqued, or the code returns after a short drive.

Tools: 10 mm socket, torque wrench, OBD‑II scanner, digital multimeter (for final verification).

Can You Still Drive With This Code?

Yes, you can drive a short distance—say, to a safe location or a nearby shop—but expect rough idle, possible stalling, and reduced power. Prolonged operation risks catalytic converter damage from unburned fuel and may cause the engine to enter “limp‑home” mode, which limits speed and RPM. If the engine stalls while you’re in traffic, you could create a hazardous situation, so treat the code as urgent.

Cost Breakdown – DIY vs. Shop Repair

DIY Savings: By doing the visual inspection and voltage check yourself, you can often avoid a shop visit entirely. The sensor itself is the most common expense, and most DIYers can replace it in under an hour with basic hand tools.

When to spend shop money: If the wiring harness is damaged deep within the engine bay, or if the ECM itself is suspect, a professional will have the proper pull‑tools and wiring diagrams to avoid creating new problems.

Preventive Maintenance Tips

• Inspect the sensor boot every 30 000 mi. Cracks allow moisture in, which accelerates corrosion.
• Keep the engine bay clean of oil and coolant splashes; contaminants can eat away at connectors.
• Check battery voltage regularly. A weak battery can cause low‑voltage spikes that confuse the CKP circuit.
• Replace timing belts/chains at the manufacturer’s interval. A stretched belt can cause the sensor to read the wrong angle, prompting a false P0335.
• Use dielectric grease on the sensor connector to repel moisture and improve electrical contact.

Which Vehicles Are Most Affected?

If you own one of the above, prioritize the visual and wiring checks early in the diagnostic process.

Related DTCs You Might Encounter

• P0325 – Crankshaft Position Sensor B Circuit Malfunction – Often appears together with P0335 when both CKP sensors are failing or the wiring is compromised.
• P0306 – Cylinder 6 Misfire Detected – A misfire can be a downstream effect of a bad CKP sensor, especially under load.
• P0420 – Catalyst Efficiency Below Threshold – Unburned fuel from misfires caused by a faulty CKP sensor can foul the catalytic converter, leading to this code.

Frequently Asked Questions

Can I drive with P0335? Yes, but only for a short distance. Expect rough idle, possible stalling, and reduced power. Prolonged driving can damage the catalytic converter and may cause a failed emissions test.

How do I fix code P0335? Start with a visual inspection of the connector and wiring, verify sensor power voltage, read live CKP data, test sensor resistance, and replace the sensor if any test fails. Clear the code and re‑test.

How long can I drive with a P0335 code? Ideally no more than a few miles to a safe repair location. If the engine stalls repeatedly, stop driving immediately.

How much does it cost to fix a P0335 code? DIY sensor replacement typically costs $45‑$120 for the part plus a few dollars for tools. A shop will charge $150‑$300 total, while a dealership may bill $200‑$400.

How to fix a P0335 code? Follow the step‑by‑step guide above: inspect, test voltage, read live data, check resistance, then replace the sensor if needed.

By systematically working through the checks outlined here, you’ll either resolve the P0335 code yourself or have concrete evidence to give a professional technician, saving time and money. Remember: a healthy crankshaft position sensor keeps your engine’s timing tight, your power smooth, and your emissions clean. Safe repairs!

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