P0335 Code Diagnosis Steps for Crankshaft Position Sensor

When your check engine light turns on and a scan tool reads P0335, you're dealing with a problem in the crankshaft position sensor circuit. This sensor tells your engine's computer exactly where the crankshaft is at any given moment. Without that signal, the engine can't time the spark or fuel injection correctly. That leads to rough running, stalling, or a no-start condition. Knowing how to diagnose a P0335 code properly saves you money, prevents unnecessary part replacements, and gets your car back on the road faster.

What does the P0335 code actually mean?

P0335 stands for "Crankshaft Position Sensor 'A' Circuit Malfunction." It triggers when the powertrain control module (PCM) detects an abnormal signal from the crankshaft position sensor (CKP). This could mean the signal is missing, erratic, or out of range. The sensor itself might be bad, but the wiring, connector, or even the reluctor ring could be the real culprit.

The crankshaft position sensor works by reading a toothed reluctor wheel attached to the crankshaft. As the wheel spins, the sensor generates a voltage signal. The PCM uses that signal to control ignition timing, fuel injection timing, and in some vehicles, variable valve timing. When this signal fails, the engine management system goes into a default or limp mode to protect the engine.

What symptoms come with a P0335 code?

Before you grab your tools, it helps to know what you're dealing with. Common symptoms tied to this code include:

Engine cranks but won't start the most common symptom, since the PCM doesn't know when to fire the injectors or spark plugs
Rough idle or misfires the PCM receives an inconsistent signal and can't maintain proper timing
Stalling while driving the engine dies suddenly because the signal drops out
Reduced power or hesitation the engine runs in a fail-safe or limp mode
Poor fuel economy incorrect timing leads to inefficient combustion
Check engine light illuminated sometimes paired with other codes like P0336, P0337, or P0338

These symptoms overlap with many other engine problems, which is why proper diagnosis matters. Replacing the sensor without testing first is one of the most common mistakes people make with this code.

What tools do you need to diagnose a P0335 code?

You don't need a full shop to test a crankshaft position sensor. Here's what helps:

OBD-II scan tool to confirm the code and check for related codes or freeze frame data
Digital multimeter (DMM) for checking resistance, voltage, and continuity
Oscilloscope (optional but helpful) to see the actual waveform pattern from the sensor
Basic hand tools sockets, screwdrivers, and a wire probe for accessing connectors
Service manual or wiring diagram specific to your vehicle's year, make, and model

If you want a deeper walkthrough on using a multimeter or oscilloscope for this repair, you can follow a detailed multimeter and oscilloscope testing guide that covers signal testing in more technical detail.

How do you diagnose a P0335 code step by step?

Step 1: Scan and record all codes

Plug in your OBD-II scanner and read all stored, pending, and history codes. Write them down. If you see related codes like P0336, P0337, P0338, P0339, or P0016, those give you clues about whether the problem is the sensor, the wiring, or the timing system. Clear the codes and see if P0335 comes back right away or after a drive cycle.

Step 2: Visual inspection

Locate the crankshaft position sensor. On most vehicles, it sits near the crankshaft pulley, the flywheel/flexplate, or the engine block. Check the sensor for physical damage, oil contamination, or loose mounting. Then inspect the wiring harness and connector. Look for:

Corroded or bent pins in the connector
Chafed, broken, or melted wires
Loose or disconnected terminals
Oil or coolant seeping into the connector

A damaged connector or a wire rubbed through against the exhaust manifold is a frequent cause of this code. Fixing a wiring issue is far cheaper than replacing the sensor.

Step 3: Test the sensor's resistance

Disconnect the CKP sensor connector. Set your multimeter to measure resistance (ohms). Place the probes on the sensor's terminals. Compare your reading to the manufacturer's specification. Typical resistance values range from 200 to 1,500 ohms depending on the vehicle, but always verify with a service manual.

Open circuit (OL/infinite resistance) the sensor coil is broken internally; replace the sensor
Short circuit (near zero ohms) internal short; replace the sensor
Within spec the sensor coil is likely fine; move on to testing the circuit

Step 4: Check for reference voltage and ground

Reconnect the sensor and turn the ignition key to the "ON" position (engine off). Back-probe the sensor connector. You should see a reference voltage (usually 5V or 12V depending on the system) on the signal wire, and a solid ground on the ground wire. If the reference voltage is missing, trace the circuit back to the PCM. The problem could be a broken wire, a corroded splice, or a PCM issue.

Step 5: Test the signal while cranking

This is the most telling test. With a multimeter set to AC voltage (for a magnetic reluctance sensor) or frequency, connect your probes to the signal and ground wires. Crank the engine and watch the reading. A working sensor will produce an AC voltage signal (typically 0.5V to 2V AC while cranking) or a frequency pulse. No signal or a weak signal points to a bad sensor or a damaged reluctor ring.

For the most accurate view, an oscilloscope shows you the waveform pattern. A healthy signal looks like a clean, repeating pattern. A damaged reluctor tooth or air gap issue shows gaps or irregular spikes in the waveform.

Step 6: Inspect the reluctor ring

If the sensor tests good but the signal is missing or erratic, the reluctor ring (also called the tone ring or trigger wheel) might be damaged. This requires visual inspection, which sometimes means removing the sensor or the timing cover. Look for broken, cracked, or missing teeth on the ring. A single missing tooth can cause intermittent misfires or trigger the P0335 code.

Step 7: Check the air gap

The distance between the sensor tip and the reluctor ring matters. If the gap is too wide, the signal weakens. If it's too tight, the sensor can make contact and get damaged. Consult your service manual for the correct specification. Some sensors are self-adjusting through their mounting, while others use shims or spacers.

What are the most common causes of a P0335 code?

Based on field repairs and shop data, the most frequent causes are:

Failed crankshaft position sensor the internal coil or electronics break down over time due to heat and vibration
Damaged wiring or connector wires near the exhaust manifold or under the engine are prone to heat damage and chafing
Corroded connector pins moisture and road salt cause corrosion that interrupts the signal
Faulty reluctor ring broken or missing teeth give the sensor nothing to read
Incorrect air gap often after an engine repair or sensor replacement where the sensor wasn't seated properly
PCM failure rare, but the PCM's internal driver circuit for the CKP sensor can fail
Timing chain/belt issues a stretched timing chain can shift the reluctor ring's position relative to the sensor, causing signal problems

What mistakes should you avoid when diagnosing this code?

The biggest mistake is replacing the sensor right away without testing. Parts stores sell a lot of CKP sensors to people who didn't need one. Here are other pitfalls to watch for:

Ignoring wiring a broken wire five inches from the connector is a five-minute fix; don't overlook it chasing a sensor problem
Not checking related codes P0016 through P0019 (cam/crank correlation codes) point to timing issues, not sensor failures
Installing a cheap aftermarket sensor some budget sensors don't produce a clean signal and can trigger the same code right after installation. OEM or high-quality OE-replacement sensors are worth the extra cost
Forgetting to clear codes after repair the PCM needs a few drive cycles to confirm the fix, but you should clear the codes so you're not chasing a ghost
Not checking the reluctor ring if the ring is damaged, a new sensor won't fix anything

For a full breakdown of P0335 diagnostic procedures, including model-specific tips, check out the detailed walkthrough linked here.

How much does it cost to fix a P0335 code?

The cost depends entirely on what's causing the code. If it's a wiring repair, you might spend under $50 on parts and do it yourself. A new crankshaft position sensor typically costs between $15 and $100 for the part, depending on your vehicle. Labor at a shop ranges from $50 to $200 for a straightforward sensor replacement, since many sensors are accessible without major disassembly.

If the reluctor ring is damaged or the PCM needs replacement, costs jump significantly. A PCM replacement can run $500 to $1,200 or more. You can review a detailed cost estimate breakdown to understand what to expect for your specific situation.

Can you drive with a P0335 code?

You technically can, but you shouldn't drive far or for long. The engine may stall without warning, especially at low speeds or when coming to a stop. In some vehicles, the engine won't start at all with this code active. If it does run, it's likely in a degraded state with rough idle, misfires, and poor throttle response. Driving with incorrect ignition timing can also damage the catalytic converter over time from unburnt fuel entering the exhaust.

Practical diagnosis checklist

Scan and record all codes note freeze frame data
Clear codes and verify P0335 returns
Visually inspect the sensor, connector, and wiring
Test sensor resistance against manufacturer specs
Check for reference voltage and ground at the connector
Test the signal output while cranking with a multimeter or oscilloscope
Inspect the reluctor ring for damage if the sensor tests good
Verify the air gap is within specification
Check for related timing chain or cam/crank correlation codes
Replace only what testing confirms is faulty

Tip: Before you buy any parts, spend 20 minutes with a multimeter testing the circuit. Most P0335 codes come down to a bad sensor or a broken wire and testing tells you which one in minutes. A vehicle safety recall search is also worth running, since some models have factory-issued technical service bulletins related to crankshaft sensor failures.