How to Test Crankshaft Position Sensor with a Multimeter

You're driving along and your engine stutters, stalls, or won't start at all. You plug in an OBD-II scanner and see P0335 Crankshaft Position Sensor "A" Circuit Malfunction. Before you spend money on a new sensor or a shop visit, a basic multimeter test can tell you whether the sensor itself is actually bad. Knowing how to test a crankshaft signal with a multimeter for a P0335 code can save you hundreds of dollars and help you avoid replacing parts that still work fine.

What Does the P0335 Code Actually Mean?

P0335 is a generic powertrain code. It tells you the engine control module (ECM) has detected a problem with the circuit from the crankshaft position sensor (CKP sensor). This small sensor monitors the position and speed of the crankshaft and sends that data to the ECM so it knows when to fire the spark plugs and injectors.

When the signal drops out, becomes erratic, or disappears entirely, the ECM sets the P0335 code. The engine may crank but not start, run rough, stall unexpectedly, or lose power under acceleration.

It's worth noting that a P0335 doesn't automatically mean the sensor is broken. The problem could also be a damaged wire, corroded connector, a bad reluctor ring, or even an ECM issue. That's exactly why testing with a multimeter matters it helps you narrow down the real cause.

What Are the Common Symptoms of a Failing Crankshaft Position Sensor?

Before you grab your multimeter, it helps to confirm your symptoms line up with a CKP sensor problem. Watch for these signs:

Engine cranks but won't start the most common symptom of a dead CKP signal
Intermittent stalling the engine dies randomly, often when warm
Rough idle or misfires the ECM can't time the ignition correctly
Check Engine Light with P0335 or related codes like P0336, P0337, or P0338
Poor acceleration or hesitation the fuel injection timing falls out of sync
No tachometer reading while cranking on some vehicles, the tachometer relies on the CKP signal

If you're seeing multiple symptoms from this list alongside a P0335 code, testing the sensor is the right next step. You can also look up specific causes by vehicle make since some models are more prone to this failure than others.

What Tools Do You Need to Test the Crankshaft Position Sensor?

The good news is you don't need expensive diagnostic equipment. Here's what to gather:

A digital multimeter that can measure resistance (ohms), AC voltage, and DC voltage
Your vehicle's repair manual or access to a reliable database like AutoZone's repair guides for wiring diagrams and sensor specs
A jack and jack stands if the sensor is located underneath the vehicle near the crankshaft pulley
A helper someone to crank the engine while you read the multimeter
Safety glasses and gloves

Where Is the Crankshaft Position Sensor Located?

The CKP sensor is usually mounted near the crankshaft pulley (harmonic balancer) at the front-bottom of the engine, or sometimes near the flywheel/flexplate at the rear of the engine block. The exact location varies by manufacturer:

GM V6 and V8 engines typically behind the harmonic balancer or near the engine block on the passenger side
Ford engines often near the crankshaft pulley at the front of the engine
Honda and Toyota usually behind the timing cover or near the oil pan area
European makes frequently near the flywheel housing at the rear of the engine

Check your repair manual or search by your specific vehicle if you're having trouble finding it. The sensor is a small device with a two- or three-pin electrical connector.

How Do You Test the Crankshaft Position Sensor with a Multimeter?

There are two main tests you can perform: a resistance test (with the engine off) and an AC voltage output test (while cranking). Both give you useful information about whether the sensor is working.

Test 1: Resistance (Ohm) Test

This test checks the internal coil of a variable reluctance (VR) type CKP sensor. Some newer vehicles use Hall-effect sensors that won't give a valid ohm reading, so know which type you have first.

Turn the ignition off and disconnect the CKP sensor connector.
Set your multimeter to the ohms (Ω) setting, typically in the 2kΩ range.
Place the multimeter leads on the sensor's signal pins (refer to your wiring diagram to identify which pins are for signal output). On a two-wire VR sensor, you're testing across the two terminals.
Read the measurement. A typical VR-type CKP sensor should read between 200 and 1,500 ohms, depending on the manufacturer. Consult your vehicle's service manual for the exact specification.
Compare your reading to the spec. A reading of OL (open loop/infinite resistance) means the internal coil is broken the sensor is bad. A reading near zero ohms means there's a short also bad.

Test 2: AC Voltage Output Test

This test confirms the sensor actually produces a signal when the crankshaft is spinning.

Disconnect the sensor connector (or back-probe the connector if you can access the wires without disconnecting).
Set your multimeter to AC voltage (V~) in the lowest range, usually 200mV or 2V AC.
Connect the multimeter leads to the sensor's output wires.
Have your helper crank the engine (don't start it just crank for a few seconds).
Watch the multimeter. A healthy VR-type CKP sensor should produce an AC voltage signal that pulses between roughly 0.3V and 1.0V or higher while cranking. The exact value depends on cranking speed and the sensor design, but you're looking for a consistent, pulsing signal not zero.

If the resistance test passes but you get no AC voltage while cranking, the problem may not be the sensor itself. The reluctor ring (the toothed wheel the sensor reads) could be damaged, or there could be excessive air gap between the sensor and the reluctor.

Test 3: Wiring and Connector Check

If the sensor checks out, move on to the wiring:

Inspect the connector for corrosion, bent pins, or moisture intrusion.
Check the harness for chafing, melted insulation, or broken wires especially where the harness passes near hot exhaust components.
Use continuity mode on your multimeter to verify each wire from the sensor connector back to the ECM connector. Any wire with no continuity is broken.
Check for short to ground by testing from each signal wire to a known good ground. You should see OL (no continuity). If you get a reading, the wire is shorted.

Many P0335 codes are actually caused by wiring problems rather than the sensor itself. If you want to understand other causes specific to your car, check our guide on fixing the engine speed sensor P0335 code.

What Do the Multimeter Readings Tell You?

Here's a quick reference for interpreting your results:

Resistance in spec + AC voltage while cranking The sensor is likely fine. Look for wiring issues, connector problems, or reluctor ring damage.
Resistance out of spec (open or short) The sensor is bad. Replace it.
Resistance in spec but no AC voltage The sensor might have a weak output, the reluctor ring could be damaged, or the air gap is too large.
Intermittent voltage drops while cranking Could indicate a failing sensor that's breaking down under heat, a loose connector, or an inconsistent reluctor ring.

What Are the Most Common Mistakes When Testing?

These errors can send you in the wrong direction:

Testing a Hall-effect sensor with an ohm reading Hall-effect sensors are solid-state and won't give meaningful resistance values. You need to check the reference voltage (typically 5V or 12V) and signal output instead.
Not checking the reluctor ring A missing, cracked, or corroded reluctor tooth will cause the same symptom as a bad sensor, but the sensor itself is fine.
Forgetting to inspect the connector Moisture, corrosion, and loose pins are extremely common causes of P0335, especially on trucks and SUVs that see water crossings or heavy rain.
Assuming a new sensor will fix the code If the wiring is damaged, a brand-new sensor will still trigger P0335. Always test before replacing.
Using the wrong multimeter setting Make sure you're on AC voltage for the output test, not DC. A CKP sensor produces an alternating signal.

Should You Replace the Sensor Yourself or Take It to a Shop?

If your multimeter test confirms the sensor is bad, replacing it is usually straightforward on most vehicles. The sensor typically costs between $15 and $80 for the part, and the job often takes 30 minutes to 2 hours depending on accessibility.

Some sensors are easy to reach from above, but many require working underneath the vehicle or removing other components for access. If you're unsure about the full cost breakdown, our crankshaft position sensor replacement cost guide breaks it down by vehicle and labor time.

If you've tested the sensor, checked the wiring, and the P0335 code keeps coming back, the issue may be deeper possibly a damaged reluctor ring requiring timing cover removal, or in rare cases, an ECM fault. That's when a professional diagnostic shop with an oscilloscope is worth the visit.

Quick Checklist Before You Call It Done

☑ Confirm the P0335 code with an OBD-II scanner and note any related codes
☑ Identify whether your vehicle uses a VR sensor or Hall-effect sensor
☑ Test sensor resistance (VR type) and compare to factory spec
☑ Test AC voltage output while cranking
☑ Visually inspect the connector and wiring for damage
☑ Check the reluctor ring for missing or damaged teeth if accessible
☑ Clear the code after any repair and road test for at least two drive cycles

Tip: After replacing a CKP sensor on many vehicles, the ECM needs to relearn the crankshaft position. Some cars require a specific relearn procedure (often involving a scan tool with bi-directional capability). Skipping this step can cause rough idle or continued codes even with a brand-new sensor installed. Always check your service manual for any required relearn steps after sensor replacement.