P0335high severityDo not driveP0335 Code: Crankshaft Position Sensor Circuit Malfunction
Written in plain English and reviewed by the eli5cars editorial team · Last reviewed June 2026
What it means in plain English
The crankshaft position sensor (CKP) is one of the most critical sensors in your engine. It monitors a toothed ring (reluctor wheel) attached to the crankshaft and tells the ECM exactly how fast the crank is spinning and where it is in its rotation at every instant. The ECM uses this to calculate ignition timing, fuel injection timing, and engine RPM. P0335 means the ECM received no signal, an intermittent signal, or a signal outside the expected range from this sensor circuit. Without crankshaft position data, the ECM cannot fire the ignition or injectors reliably — the engine may refuse to start or stall suddenly while driving. This is a high-priority code.
⛔ Do not drive with this code active
This fault can cause immediate mechanical or safety damage. Have the vehicle towed or inspected before driving.
Most likely causes — ranked
#1 Failed crankshaft position sensor
most likelyFix: The CKP sensor itself is a common failure, particularly on high-mileage engines. The sensor is usually located near the crankshaft pulley (front of engine) or at the rear of the block near the flywheel/flexplate. Test the sensor's resistance with a multimeter (spec varies by sensor type — compare to factory spec). A Hall-effect sensor also needs a 5 V reference and a clean ground to produce a signal. If reference and ground check out but signal is absent during cranking, replace the sensor.
#2 Damaged, broken, or shorted wiring to the CKP sensor
likelyFix: The CKP sensor harness often runs close to rotating components and heat sources near the bottom of the engine. Look for cracked insulation, chafed wires, or corroded connector pins. Wiggle the harness while watching live RPM data on a scanner — an intermittent P0335 that appears only under vibration or heat usually points to a wiring fault. Repair any damaged sections and apply heat-resistant wire loom.
#3 Damaged or contaminated reluctor wheel (tone wheel)
likelyFix: The reluctor wheel is a ring with precision-spaced teeth pressed onto the crankshaft. A broken tooth, crack, or heavy debris (metal shavings in oil, buildup) can disrupt the magnetic field the sensor reads. If the sensor and wiring check out, inspect the reluctor ring for damage. This often requires removing the crankshaft pulley or accessing the area near the flywheel. A damaged reluctor wheel typically means engine or crankshaft work.
#4 Improper sensor air gap or sensor knocked out of position
possibleFix: The CKP sensor must be positioned within a precise air gap from the reluctor teeth — typically 0.020–0.050 inches (varies by vehicle). A sensor that is loose, damaged by impact (from road debris), or incorrectly installed after previous work may produce an erratic signal. Inspect the sensor mount, tighten or reposition as needed, and check the gap with a feeler gauge if the design allows it.
Check engine light on? Get a free code scan
If your check engine light is on, most auto-parts stores (AutoZone, O'Reilly, Advance) will read the code for FREE — no purchase required, just walk in. Bring the code back here and look it up at eli5cars.com/obd2 for the plain-English explanation.
Note: a scan only helps when there's an active fault code. For purely mechanical symptoms (noises, vibrations, leaks), a scan may show nothing — the suspects listed above are your starting point.
Want to read the codes yourself?
First, the free option: AutoZone, O’Reilly, and Advance Auto Parts read your codes for free — no purchase needed. That’s the cheapest way to get the code to look up here. If you’d rather have your own so you can check anytime (and clear a code after a fix), the Veepeak OBDCheck BLE is an inexpensive, reliable plug-in reader that pairs with a free phone app and works on any car sold since 1996.
See the Veepeak OBD2 scanner on AmazonAffiliate link — we may earn a commission at no extra cost to you. Details.
Frequently asked questions
Can I drive with P0335?
No — or only to get to a shop immediately. The crankshaft position sensor is essential for the engine to run at all. The engine may stall without warning and may not restart. Driving on the highway with P0335 is risky. If the car is running, drive directly to a nearby shop or have it towed.
My car cranks but won't start and I have P0335. Is the sensor definitely the problem?
Very likely, but confirm with a scanner that shows live engine RPM data. If the RPM gauge reads 0 while cranking, the ECM is not receiving the crank signal — that points directly to the sensor, its wiring, or the reluctor wheel. If RPM shows a signal during cranking, the issue is elsewhere (fuel, spark).
How hard is it to replace a crankshaft position sensor myself?
On many vehicles it's a straightforward 30–60 minute job with basic hand tools — find the sensor, unplug it, remove one or two bolts, and install the new one. On some vehicles it's buried behind the starter, timing cover, or requires lifting the car. Look up a vehicle-specific video before starting. Difficulty ranges from easy to moderate depending on your car.
Where can I get a free scan for P0335?
AutoZone, O'Reilly, and Advance Auto Parts offer free OBD2 scans. Note every code present — if you also see cam sensor or timing correlation codes, share all of them with your mechanic, as the combination matters for diagnosis.