Crankshaft Position Sensor vs Camshaft Sensor Multimeter Diagnosis for P0335 Code

That check engine light just came on, you plugged in your OBD-II scanner, and it handed you a P0335 code. Now you're staring at two sensors that sound almost identical the crankshaft position sensor and the camshaft position sensor and you're not sure which one to test first or how a multimeter fits into the picture. This is a common sticking point for DIY mechanics, and getting it wrong means wasting money on parts that weren't broken in the first place. Here's how to tell these sensors apart, test them properly with a multimeter, and figure out what's actually triggering that P0335 code.

What Does a P0335 Code Actually Mean?

P0335 stands for "Crankshaft Position Sensor 'A' Circuit Malfunction." Your engine control module (ECM) relies on the crankshaft position sensor (CKP) to know where the crankshaft is at any given moment. That information determines ignition timing and fuel injection. When the ECM detects an open circuit, erratic signal, or no signal at all from the CKP sensor, it sets the P0335 code.

The tricky part is that a failing camshaft position sensor (CMP) can sometimes cause symptoms that look a lot like a CKP problem. Both sensors work together to keep the engine's timing in sync. If one sends a garbage signal, the other can't compensate and the ECM may not always distinguish between the two cleanly on its own. That's where a multimeter comes in.

Why Do People Confuse the Crankshaft and Camshaft Sensors?

Both sensors do similar jobs: they monitor rotating components and send electrical signals back to the ECM. They often look alike physically, use the same type of wiring (typically a three-wire connector with a reference voltage, signal, and ground), and can produce similar symptoms when they fail rough idle, stalling, no-start conditions, or poor fuel economy.

The key difference is what they monitor and where they're located:

Crankshaft position sensor (CKP) mounted near the crankshaft, usually at the front or rear of the engine block. It reads a reluctor ring or tone wheel attached to the crankshaft. This sensor is the primary signal for engine speed (RPM) and piston position.
Camshaft position sensor (CMP) mounted near the camshaft, often on the cylinder head or timing cover. It reads a reluctor on the camshaft sprocket. This sensor tells the ECM which cylinder is on its compression stroke.

Since P0335 points specifically at the crankshaft position sensor circuit, that's your starting target. But a bad CMP sensor can cause enough timing confusion to indirectly affect CKP readings, so testing both isn't overkill it's smart troubleshooting.

How Do You Test a Crankshaft Position Sensor With a Multimeter?

There are two types of CKP sensors you'll run into, and the testing method depends on which one your vehicle uses.

Testing a Magnetic (Variable Reluctance) CKP Sensor

This type generates its own AC voltage as the reluctor ring passes by. It usually has two wires.

Set your multimeter to AC voltage. Disconnect the sensor connector.
Back-probe the sensor terminals or connect directly to the sensor pins.
Crank the engine (or spin the crankshaft by hand with a socket on the harmonic balancer bolt).
Read the output. A healthy magnetic CKP sensor typically produces between 0.5V and 1.5V AC while cranking. If you get 0V or close to it, the sensor is likely dead.
Check resistance. Switch the multimeter to ohms and measure across the two sensor terminals. Most magnetic CKP sensors spec out between 200 and 1,500 ohms, depending on the manufacturer. Check your vehicle's service manual for the exact range. An open reading (OL) or a reading near zero means the sensor has failed.

For detailed step-by-step resistance and voltage readings, you can check out this guide on crankshaft position sensor voltage and resistance readings.

Testing a Hall-Effect CKP Sensor

This type uses three wires reference voltage (usually 5V or 12V from the ECM), signal, and ground. It needs power to operate.

With the key on (engine off), check for reference voltage. Back-probe the reference wire and ground. You should see around 5V or 12V depending on the system.
Check the ground wire for continuity to the battery negative terminal.
Switch to DC voltage on the signal wire. Crank the engine and watch the multimeter. A working Hall-effect sensor will pulse between roughly 0V and 5V (or 0V to 12V). If the voltage stays flat, the sensor or its circuit has a problem.
Check for shorts. Measure resistance between each pin and the sensor housing. There should be no continuity (infinite resistance) between any pin and the housing.

If your vehicle won't crank at all with this code, this no-crank no-start multimeter continuity test walkthrough covers exactly what to check.

How Do You Test the Camshaft Position Sensor With a Multimeter?

The CMP sensor testing process is nearly identical to the CKP process because most vehicles use the same type of sensor for both. The difference is location and what you're measuring.

Magnetic CMP sensor: Measure AC voltage output while the engine cranks. Expect 0.3V to 1.0V AC. Check resistance between the two pins usually 200 to 1,000 ohms.
Hall-effect CMP sensor: Verify reference voltage on the power wire, check the ground for continuity, and watch for voltage pulsing on the signal wire during cranking.

The important thing is to compare your readings to the specs for your specific vehicle. Not all sensors read the same, and guessing can send you down the wrong path. If you want a side-by-side breakdown of both sensor tests, this crankshaft vs camshaft sensor multimeter diagnosis comparison covers it in detail.

What Are the Most Common Mistakes When Diagnosing P0335?

Getting the wrong answer on a P0335 diagnosis usually comes down to one of these errors:

Replacing the sensor without testing it. This is the single biggest waste of money. A P0335 code doesn't automatically mean the sensor is bad. The wiring, connector, or even the reluctor ring could be the problem.
Not checking the wiring harness. A frayed wire, corroded connector pin, or loose ground can trigger P0335 even with a perfectly good sensor. Always do a visual inspection and check continuity on the harness before buying parts.
Ignoring the reluctor ring. If the tone wheel is damaged, cracked, or has a missing tooth, the sensor will send a bad signal regardless of its own condition. You usually can't see this without removing the sensor.
Testing at the ECM connector instead of the sensor. Testing at the ECM end can introduce false readings if there's a wiring issue between the sensor and the ECM. Test as close to the sensor as possible first.
Assuming P0335 can only be the CKP sensor. While P0335 points to the crankshaft sensor circuit, a failing camshaft sensor can create timing errors that cascade into CKP-related codes. If your CKP tests good, don't skip testing the CMP.

When Should You Test Both Sensors Instead of Just One?

You should test the camshaft sensor alongside the crankshaft sensor in these situations:

The CKP sensor tests within spec, but the code keeps coming back after a reset.
You're experiencing intermittent stalling or rough running that comes and goes rather than a hard no-start.
The vehicle has a timing chain or belt issue a stretched chain can cause both sensors to read out of sync.
You've already replaced the CKP sensor and the code returned. In this case, the problem may have never been the crankshaft sensor at all.

Can a Bad Camshaft Sensor Cause a P0335 Code?

Not directly. The P0335 code is tied to the crankshaft position sensor circuit specifically. However, the ECM cross-references both sensors to validate timing. If the camshaft sensor sends a corrupted signal, the ECM may detect a mismatch it interprets as a CKP circuit fault. This is more common on some makes particularly certain Toyota, Nissan, and GM vehicles where the two sensor signals are tightly coupled in the ECM's logic.

So yes, it's possible to chase a P0335 code that's actually caused by a bad CMP sensor, which is another reason to test both.

What Should You Check After Replacing the Sensor?

If you've confirmed the sensor is bad and replaced it, do these follow-up steps before calling the job done:

Clear the code with your scan tool. Don't just disconnect the battery use a proper OBD-II scanner so the ECM fully resets the code monitor.
Start the engine and let it idle for a few minutes. Watch for smooth idle, normal RPM behavior, and no new codes.
Drive the vehicle through a full drive cycle. This lets the ECM run all its self-tests. If the code comes back, the issue is likely in the wiring, connector, or reluctor ring not the sensor itself.
Re-check with the multimeter. Verify the new sensor's voltage and resistance readings match spec. New parts can be defective out of the box it happens more than people think.

Quick Diagnostic Checklist for P0335

Read the code and note any companion codes (P0340, P0341, P0016, P0017).
Identify your sensor type magnetic (two wires) or Hall-effect (three wires).
Visually inspect the CKP sensor connector, wiring, and harness for damage or corrosion.
Test CKP sensor resistance with the multimeter set to ohms. Compare to factory specs.
Test CKP sensor output voltage during cranking (AC voltage for magnetic, DC voltage for Hall-effect).
Check reference voltage and ground at the sensor connector (Hall-effect sensors only).
Test the CMP sensor using the same method if CKP readings are within spec.
Inspect the reluctor ring if possible, or listen for unusual noises that might indicate timing chain damage.
Check wiring continuity between the sensor connector and the ECM pins.
Replace, clear, and verify then run a full drive cycle to confirm the repair holds.