P0335 Code: Crankshaft Position Sensor A Circuit

What happens if you don't fix it

Symptoms you can actually notice

• Cranks but won't start
• Stalls randomly
• Tach drops to zero while driving

What the computer is actually complaining about

The crankshaft position sensor reads a toothed wheel on the crank and tells the ECU where the pistons are and how fast they move. The ECU uses that signal to fire the coils and the injectors. Lose the signal for a moment and the ECU stops firing. The code sets when the ECU sees no crank signal while the starter is turning.

Most likely causes, cheapest check first

What you need in your hands

• OBD-II scanner with live data

  A $25 Bluetooth reader plus a free app shows engine rpm during cranking. If rpm stays at zero while the starter spins, the sensor is not reporting.

• Digital multimeter

  A basic meter runs $15 to $25. It checks the sensor reference voltage and the ground at the connector.

• Crankshaft position sensor Optional

  The part runs $25 to $90. Buy it after the wiring check, not before.

Test it yourself, step by step

Do these in order. Each step tells you what to do, what to look at, what counts as fine, what counts as broken, and what you will actually see.

1. 1 Plug the scanner into the trapezoid port under the dash on the driver side, above your left knee. Key to ON, then crank the engine for five seconds while you watch the rpm reading on live data.

   Look at

   Whether the rpm number moves at all while the starter is turning the engine over.

   Fine if

   Rpm reads 150 to 300 while cranking, then settles near 700 once the engine fires.

   Broken if

   Rpm sits at zero the whole time the starter spins. The ECU is getting no crank signal, and the engine will not run like this.

   What you'll see A number on the screen that jumps up while the starter turns. A flat zero with a spinning starter is the confirmation.

2. 2 Open the hood and look at the front of the engine, below the valve cover, on the passenger side. The sensor is a black plastic cylinder about the size of your thumb, bolted next to the crank pulley with one 10mm bolt and one wire.

   Look at

   Whether the sensor body is cracked, whether the mounting bolt is tight, and whether the tip has metal shavings stuck to it.

   Fine if

   Body intact, bolt tight, tip clean with only light dust on it.

   Broken if

   Cracked housing, a loose bolt letting the sensor back away from the wheel, or a tip packed with gray paste. Any of those kills the signal.

   What you'll see A small dark cylinder sitting close to a toothed wheel, with a two or three wire plug coming off the top and a clean flat face.

3. 3 Follow the sensor wire up along the front of the engine to the connector clipped beside the alternator. Unclip it and pull the two halves apart, then look straight into the pins.

   Look at

   The pins for green crust or white powder, and the wire for a rub mark where it passes the belt guard.

   Fine if

   Pins clean and dry, insulation unbroken from the sensor to the connector.

   Broken if

   Green crust in the plug, or a rubbed spot with bare copper showing. A chafed wire breaks the signal when the engine moves.

   What you'll see A small gray plug with two or three pins in a row, and clean metal where you look straight in. Any green means water got in.

4. 4 Set the multimeter to DC volts. Key on, engine off. Back probe the reference pin at the harness half of the connector, using a thin pin beside the probe, and touch the other probe to the engine block as ground.

   Look at

   The voltage on the reference wire with the key on, and the resistance from the ground wire to the block.

   Fine if

   Reference reads about 5 volts and the ground wire reads under 1 ohm to the block.

   Broken if

   Reference reads 0 volts or battery voltage, or the ground reads over 5 ohms. The sensor is fine and the harness or the ground is the fault.

   What you'll see A steady 5.0 on the display, and a resistance reading under 1 ohm on the ground leg. Anything else means wiring.

5. 5 If the wiring passes, unbolt the old sensor from the front of the engine on the passenger side and pull it straight out of the bore. Wipe the bore clean, then push the new sensor in until it bottoms out and snug the 10mm bolt.

   Look at

   Whether the new sensor sits flush against the timing cover, and whether the engine starts on the first crank.

   Fine if

   Engine fires within two seconds of cranking, rpm reads normally, and P0335 stays off through ten start cycles.

   Broken if

   The engine still cranks with no rpm reading. At that point the toothed wheel behind the sensor is damaged, and that is a bigger job.

   What you'll see The old sensor sliding out with a light film of oil on the tip, and the new one going in with a firm stop, not a wobble.

What the repair costs

Reference range compiled from 2 source type(s), as of 2026-11. This is not a quote — actual cost depends on your vehicle, region, and which part turns out to be the real cause.

Basis: reference · 2 source types cross-checked · Data as of 2026-11 · Confidence: medium

How to confirm it's really fixed

✓ Clear the code and drive 30 miles with a few full stops and restarts. Watch the rpm reading on live data during each start. If rpm registers on every crank and P0335 stays off through ten start cycles, the circuit is sound. If it returns, the reluctor wheel is the next thing to inspect.

Common questions