How to Test Crankshaft Position Sensor P0335 with a Multimeter

When your check engine light comes on and a scan tool throws a P0335 code, your crankshaft position sensor is trying to tell you something. This sensor feeds engine speed and position data to your car's computer. Without that signal, the engine may not start, may stall without warning, or may run rough enough to leave you stranded. Knowing how to test a crankshaft position sensor with a multimeter can save you a tow bill, help you avoid replacing parts that are still good, and get you back on the road faster.

What Does the P0335 Code Actually Mean?

P0335 stands for "Crankshaft Position Sensor 'A' Circuit Malfunction." Your engine control module (ECM) monitors the signal coming from the crankshaft position sensor. When that signal drops out, becomes erratic, or falls outside expected voltage or resistance values, the ECM sets this code. The problem could be the sensor itself, the wiring between the sensor and the ECM, or the sensor's tone ring (reluctor). A multimeter helps you figure out which one it really is before you spend money on guesswork.

What Tools Do I Need?

A digital multimeter capable of measuring resistance (ohms), AC voltage, and DC voltage
Basic hand tools to remove the sensor (usually a 10mm bolt)
Your vehicle's repair manual or a reliable spec sheet for the correct resistance and voltage ranges
Jack stands or ramps if the sensor is underneath the engine

Where Is the Crankshaft Position Sensor Located?

The location varies by vehicle. On many GM and Chevrolet models, the sensor sits near the crankshaft pulley at the front bottom of the engine. On some vehicles, it mounts on the transmission bell housing near the flywheel. Check your specific vehicle's service manual so you are not crawling around looking in the wrong spot. If you drive a GM vehicle, we have a detailed walkthrough covering the resistance measurement procedure for GM and Chevrolet crankshaft sensors that may help.

How Do I Test the Crankshaft Position Sensor With a Multimeter?

Step 1: Test the Sensor's Resistance (Ohms Test)

Turn off the ignition and disconnect the sensor's electrical connector.
Set your multimeter to the resistance (ohms) setting.
Place one probe on each of the sensor's two terminals.
Compare the reading to the manufacturer's spec. Most crankshaft position sensors fall between 200 and 1,000 ohms, but your vehicle may differ. Always verify with your service manual.
If the reading shows OL (open loop/infinite resistance) or is far outside spec, the sensor is likely bad and needs replacement.

Step 2: Check for a Short to Ground

Keep the sensor disconnected.
Set the multimeter to continuity or resistance.
Touch one probe to a sensor terminal and the other to a clean, bare-metal ground on the engine.
You should get no continuity (OL reading). If you do get continuity, the sensor's internal winding is shorted to ground and the sensor must be replaced.

Step 3: Test the Wiring Harness Back to the ECM

Disconnect the sensor connector and the ECM connector.
Set your multimeter to continuity.
Test each wire from the sensor plug to its corresponding pin at the ECM. Each wire should show continuity with low resistance.
Also test each wire to ground. You should see no continuity to ground on signal or reference wires.

If your car shows a no-crank, no-start condition alongside a P0335 code, this wiring continuity check is especially important because a broken wire can prevent the signal from ever reaching the ECM.

Step 4: Check the Sensor's Output Signal (AC Voltage Test)

Reconnect the sensor to its harness.
Set the multimeter to AC voltage (millivolts range if possible).
Back-probe the signal wire at the connector with the sensor still installed.
Have a helper crank the engine. You should see a small AC voltage signal, typically between 0.5V and 1.5V AC while cranking.
If you see no voltage at all, the sensor is not producing a signal confirm the wiring is good before replacing the sensor.

Should I Test the Sensor on the Bench or on the Car?

Both have value. The resistance test (Steps 1 and 2) works with the sensor removed or still installed. The output signal test (Step 4) requires the sensor to be in place and the engine cranking. Many mechanics start with the quick resistance test on the car. If that passes, they move to the signal test. If that fails too, they pull the sensor and inspect it physically for damage or debris. For a full breakdown of testing with the sensor removed, see our article on how to test a crankshaft position sensor with a multimeter step by step.

What Are the Most Common Mistakes?

Testing with the wrong multimeter setting. Resistance tests need ohms mode. Signal tests need AC volts. Mixing them up gives meaningless numbers.
Ignoring the wiring. A new sensor will not fix a broken or corroded wire. Always test the harness.
Not using the correct spec. Saying "it should be around 500 ohms" is useless if your car's sensor is spec'd at 850–1,150 ohms. Look up the number for your exact year, make, and model.
Forgetting to clear the code after testing. If you fix the issue but do not clear the P0335 code, the light stays on and you might think the fix did not work.
Assuming the tone ring is fine. A cracked or missing tooth on the reluctor ring will cause the same code even with a brand-new sensor installed.

What If All My Multimeter Tests Pass?

If resistance is in spec, the sensor is not shorted to ground, the wiring checks out, and you still see a P0335 code, the issue may be:

An intermittent fault that only shows up when the engine is hot (try testing after a drive)
A damaged tone ring behind the harmonic balancer or on the flywheel
An ECM issue, though this is far less common than a bad sensor or wiring
Excessive air gap between the sensor and the tone ring due to a worn mounting surface

Quick Reference: Normal vs. Bad Readings

Test	Normal	Bad
Resistance (ohms)	200–1,500 Ω (check your spec)	OL, 0, or way outside spec
Short to ground	OL (no continuity)	Continuity present
AC signal while cranking	0.5–1.5V AC	0V or erratic jumps
Wiring continuity	Low resistance end-to-end	OL or high resistance

For a broader reference on sensor testing procedures, the NAPA Know How glossary entry on crankshaft position sensors is a useful starting point.

Quick Checklist Before You Replace the Sensor

Resistance reading matches factory spec for your vehicle
No short to ground on either terminal
Both signal and reference wires have continuity from sensor to ECM with no shorts to ground
AC voltage signal present while cranking (if sensor is installed)
Visual inspection shows no cracked housing, damaged connector pins, or metal debris on the sensor tip
Tone ring inspected for missing or damaged teeth
Code cleared with a scan tool after any repair

Work through this list in order. If the sensor fails the first test, you likely have your answer. If it passes all of them, the problem is probably upstream wiring, tone ring, or less likely, the ECM. Either way, a multimeter and a methodical approach keep you from throwing parts at the problem.