How to Use a Code Reader to Diagnose Crankshaft Position Sensor Clicking on Left Turns

You're driving and hear a clicking sound every time you turn left. You suspect the crankshaft position sensor, but you're not sure. That's where a code reader comes in. Knowing how to use a code reader to isolate a crankshaft position sensor clicking sound during a left turn saves you money, time, and the frustration of replacing parts that aren't broken. Instead of guessing, you can pull diagnostic trouble codes (DTCs) from your car's computer and narrow down the problem before touching a single bolt.

What causes a clicking sound from the crankshaft position sensor when turning left?

The crankshaft position sensor (CKP) monitors the position and rotational speed of the crankshaft. It sends this data to the engine control module (ECM), which uses it to control fuel injection and ignition timing. When this sensor or its wiring develops a fault, you might notice unusual symptoms including clicking or ticking noises that seem tied to specific driving conditions.

A clicking sound that only happens during left turns usually points to a wiring or connector issue rather than the sensor itself. When you turn the steering wheel left, the engine and components shift slightly on their mounts. If the CKP sensor connector is loose, the wiring harness is chafed against another component, or the sensor bracket is cracked, that movement can create intermittent contact. Each moment of lost contact produces a click or a brief misfire that sounds like a click.

Can a code reader really help isolate this specific problem?

Yes. A code reader or OBD2 scanner accesses stored and pending diagnostic trouble codes in your vehicle's ECM. When the crankshaft position sensor sends erratic or missing signals, the ECM logs specific codes. The most common CKP-related codes include:

P0335 Crankshaft Position Sensor "A" Circuit Malfunction
P0336 Crankshaft Position Sensor "A" Circuit Range/Performance
P0337 Crankshaft Position Sensor "A" Circuit Low Input
P0338 Crankshaft Position Sensor "A" Circuit High Input
P0339 Crankshaft Position Sensor "A" Circuit Intermittent

P0339 is especially relevant here. The word "intermittent" matches exactly what you're experiencing a problem that comes and goes depending on driving conditions, like turning left. If you pull this code, you've narrowed the issue significantly.

That said, a code reader alone won't always give you the full picture. You'll want the right diagnostic tools to complete this job properly, which may include a multimeter and a basic inspection mirror.

Step-by-step: How to use a code reader to isolate the CKP sensor clicking issue

Step 1 Connect the code reader

Locate your vehicle's OBD2 port. In most cars, it's under the dashboard on the driver's side, near the steering column. Plug in your code reader and turn the ignition to the "On" position without starting the engine. Wait for the scanner to establish communication with the ECM.

Step 2 Read stored and pending codes

Navigate to the "Read Codes" or "Diagnostic Codes" menu on your scanner. Write down every code stored, pending, and history. You're looking for anything in the P0335–P0340 range, but don't ignore other codes. Sometimes a failing CKP sensor triggers secondary codes for camshaft position (CMP) correlation or misfires.

Step 3 Clear the codes and reproduce the problem

Clear all codes, then take the car for a drive. Make several left turns at moderate speed. Pay attention to the clicking sound and note when it happens during acceleration into the turn, at a specific speed, or only on sharp turns. After the drive, reconnect the code reader and check for new or pending codes.

If P0339 or another CKP code reappears after the test drive, you've confirmed the sensor or its circuit is the source. If no codes return but you still hear clicking, the noise may be mechanical possibly a CV joint, wheel bearing, or even a loose heat shield.

Step 4 Check freeze frame data

Most mid-range OBD2 scanners can display freeze frame data. This shows you the exact engine conditions at the moment a code was set RPM, engine load, vehicle speed, and coolant temperature. Compare this data to when you heard the click during your test drive. If the freeze frame shows the code was set during a turn or at low RPM, that strengthens the connection to your left-turn symptom.

If you need a scanner with freeze frame capability and live data, an OBD2 scanner built for this type of diagnosis makes the process much easier.

Step 5 Inspect the sensor and wiring physically

Pop the hood and locate the CKP sensor. On most engines, it's mounted near the crankshaft pulley at the front-bottom of the engine, or near the flywheel at the back. Check these things:

Connector condition Look for corrosion, bent pins, or a connector that doesn't click fully into place.
Wiring routing Follow the harness from the sensor to the main loom. Look for chafing, especially where the wire passes near moving parts or sharp edges.
Mounting Make sure the sensor is tight in its bracket. A loose sensor can shift during turns and cause signal dropouts.
Air gap Some CKP sensors have a specified gap between the sensor tip and the reluctor ring. If this gap is too wide (due to a missing shim or a cracked mounting surface), the signal weakens.

Step 6 Test the sensor with a multimeter

Use a multimeter to check the sensor's resistance and output voltage. Disconnect the sensor connector and measure resistance across the two signal pins. A typical reading for a magnetic CKP sensor is between 200 and 1,000 ohms, but always check your vehicle's service manual for the exact spec. If the reading is open (infinite resistance) or shorted (near zero), the sensor is bad.

For a more dynamic test, set the multimeter to AC voltage, reconnect the sensor, and crank the engine. You should see a fluctuating AC voltage signal usually between 0.5V and 1.5V AC. An erratic or flat signal during cranking confirms a failed sensor.

A quality multimeter designed for automotive sensor testing will give you more accurate readings than a cheap general-purpose meter.

What are the most common mistakes people make during this diagnosis?

Replacing the sensor without testing. A lot of people read a CKP code and immediately buy a new sensor. But the code might point to a wiring problem, a bad ground, or even a timing chain issue. Test first, replace second.

Ignoring pending codes. Stored codes are obvious. Pending codes are easy to skip over. But a pending P0339 is just as important it means the ECM has detected an intermittent fault that hasn't yet triggered the check engine light. Read every category of code.

Not checking for TSBs. Technical Service Bulletins from your vehicle's manufacturer sometimes address known CKP sensor issues, including updated wiring harnesses or revised sensor mounting hardware. Check the NHTSA recall and TSB database for your make and model.

Confusing CKP noise with CV joint clicking. A worn CV joint is one of the most common causes of clicking during turns. If your code reader shows no CKP-related codes and the sensor tests within spec, have your CV axles inspected before pursuing the sensor further.

Clearing codes and not driving long enough. Some monitors require specific drive cycles to complete. If you clear codes and only drive around the block, pending codes may not have time to set again. Drive at least 15–20 minutes with multiple left turns to give the ECM enough data.

What should you do after confirming the CKP sensor is the problem?

Once your code reader and physical inspection confirm the crankshaft position sensor is the source of the clicking during left turns, here's the typical repair path:

If it's a wiring issue Repair or replace the damaged section of the harness. Use weatherproof connectors and loom the repaired section to prevent future chafing.
If the sensor is loose Reinstall it with the correct torque spec and check the mounting surface for cracks.
If the sensor is failed Replace it with an OEM or high-quality aftermarket unit. Cheap sensors from unknown brands often fail within months.
After the repair Clear all codes with your code reader and perform another test drive with left turns. Confirm no new codes appear and the clicking is gone.