P0335 – Crankshaft Position Sensor “A” Circuit

Last updated: April 4, 2026

DTC P0335 is an ISO/SAE controlled powertrain code that indicates a fault in the Crankshaft Position Sensor “A” Circuit. The crankshaft position (CKP) signal is one of the primary inputs the engine control module uses to determine engine speed and crankshaft angle so it can manage ignition timing, fuel injection timing, and engine synchronization. When the module detects that the CKP “A” circuit is not behaving electrically as expected—such as a missing signal, an implausible signal, or a circuit condition that prevents accurate interpretation—it stores P0335 and may illuminate the malfunction indicator lamp (MIL). Depending on how the circuit fails, the engine may start and run poorly, stall, or crank without starting because the controller cannot reliably determine crank position.

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P0335 Quick Answer

P0335 indicates a problem in the Crankshaft Position Sensor “A” Circuit. Because the code is a circuit fault (not a guaranteed sensor failure), diagnosis should focus on wiring, connectors, power and ground (if applicable), and signal integrity between the sensor and the control module before replacing components.

What Does P0335 Mean?

P0335 – Crankshaft Position Sensor “A” Circuit means the powertrain control module has detected an electrical fault affecting the CKP sensor “A” circuit. In practical terms, the controller is not receiving a crankshaft position signal it can use consistently, or it detects circuit behavior that falls outside expected limits for that input.

The wording “Circuit” is important: it includes the sensor’s electrical path and the controller’s ability to read it. Depending on sensor design and vehicle architecture, the circuit may involve a sensor power supply, a sensor ground, a signal wire, shielding, splices, and the controller input pin. P0335 sets when the controller’s internal checks determine that the circuit cannot be trusted for accurate engine speed/position calculation.

Theory of Operation

The crankshaft position sensor monitors a rotating target attached to the crankshaft (often a toothed or slotted wheel). As the crankshaft rotates, the sensor produces an electrical signal that changes with tooth passage. The control module interprets this pattern to calculate engine RPM and crankshaft angle, and it uses that information to coordinate ignition and injection events.

Because this input is foundational for engine management, the controller continuously evaluates CKP circuit health. If the CKP “A” circuit signal is missing when it should be present, shows electrical characteristics that indicate an open or short, or behaves in a way that does not meet the controller’s expected logic, the controller stores P0335. The result may range from a MIL with drivability concerns to a stall or no-start if the controller cannot maintain synchronization.

Symptoms

• Malfunction indicator lamp (MIL) illuminated
• Crank/no-start (engine cranks normally but does not start)
• Engine stalls, potentially without warning
• Extended cranking time before starting
• Intermittent hesitation, misfire-like behavior, or rough running if the CKP signal drops out
• Unstable or missing engine speed (RPM) reading on scan tool data during cranking or running
• Reduced performance if the controller enters a fail-safe strategy

Common Causes

• Open circuit in the CKP “A” signal wiring (broken wire, damaged splice, or poor terminal contact)
• Short to ground in the CKP “A” circuit wiring
• Short to voltage in the CKP “A” circuit wiring
• Loose, corroded, contaminated, or damaged CKP sensor connector or controller connector
• Insufficient sensor power supply or poor sensor ground (on sensor types that require a dedicated power/ground)
• Sensor mounting problems that affect signal generation (loose mounting, improper seating, or contamination at the sensor tip)
• Damage or defects at the crankshaft target/reluctor that prevent a usable signal from being generated
• Controller input circuit issue after all external circuit and signal checks are proven good

Diagnosis Steps

Tools you’ll need: A scan tool capable of reading codes, freeze frame, and live data; a DVOM for voltage, resistance, and voltage-drop testing; appropriate back-probing or terminal test leads; and service information for the specific vehicle (connector pinouts, sensor type, and circuit routing). A lab scope is strongly recommended to verify CKP signal integrity during cranking and under vibration.

1. Confirm the DTC and capture data. Verify P0335 is present and record freeze frame information. Note battery voltage, engine RPM at the time of fault, and whether the code is pending or confirmed. Check for any additional related DTCs and document them before clearing anything.
2. Check for an RPM signal while cranking. With the scan tool on live data, observe engine RPM during cranking. If RPM remains at or near 0, the controller is not receiving a usable CKP signal, which supports a circuit/signal integrity problem that must be tested at the sensor and controller.
3. Perform a thorough visual inspection of the CKP “A” circuit. Inspect harness routing and protection near rotating components, hot surfaces, brackets, and the front or rear of the engine where the CKP wiring commonly passes. Look for chafing, pinching, melted insulation, oil contamination, and prior repair areas.
4. Inspect connectors and terminals at the CKP sensor. Disconnect the sensor connector and check for moisture, corrosion, damaged seals, bent pins, pushed-out terminals, and poor terminal tension. Lightly tug on each wire to identify broken conductors hidden under insulation.
5. Verify the power and ground (when applicable). Using service information, identify whether the CKP sensor uses a dedicated power feed and ground. Back-probe the connector and test supply voltage and ground quality while cranking. Use voltage-drop testing on the ground circuit under load to find high resistance that may not show up on a static resistance check.
6. Check for opens and shorts in the CKP “A” circuit wiring. With the circuit safely isolated as directed by service information, test continuity end-to-end between the sensor connector and the controller connector. Then test for short-to-ground and short-to-voltage conditions on the signal and related circuits. If possible, load-test suspect circuits to reveal high-resistance faults.
7. Verify CKP signal integrity during cranking. Use a lab scope to observe the CKP waveform at the sensor connector and compare it to the waveform at the controller input (when accessible). Look for dropouts, distortion, flatlining, or electrical noise that could cause the controller to flag a circuit fault.
8. Wiggle-test the harness and connectors. While monitoring CKP signal or RPM data during cranking or idle (if the engine runs), gently manipulate the harness at known stress points and connector bodies. Any immediate RPM loss or waveform interruption helps pinpoint an intermittent circuit problem.
9. Inspect sensor mounting and the crankshaft target. Verify the sensor is securely mounted and properly seated. Inspect for debris at the sensor tip and for physical damage in the sensor area. If access allows, inspect the crankshaft target/reluctor for damage or conditions that could prevent generation of a stable CKP signal.
10. Evaluate the controller input last. If wiring integrity, connector condition, power/ground (if applicable), and the CKP signal at the sensor are all verified good—and the signal does not appear correctly at the controller—then investigate the controller-side connector, pin fit, and the controller input circuit per service procedures. Only consider controller replacement after all external causes are proven absent.

Professional tip: For a crank/no-start with P0335, prioritize checking live RPM during cranking and validating the CKP waveform with a scope. A stable, repeatable signal at the sensor that fails to appear at the controller strongly points to a circuit issue between the two, while no usable signal at the sensor points to sensor power/ground (if used), sensor condition, mounting, or target-related problems.

Possible Fixes

• Repair or replace damaged wiring in the Crankshaft Position Sensor “A” circuit
• Clean, repair, or replace damaged terminals/connectors related to the CKP “A” circuit
• Correct shorts to ground or shorts to voltage affecting the CKP “A” circuit
• Restore proper sensor power supply and/or ground integrity (where applicable)
• Correct CKP sensor installation concerns (secure mounting, proper seating, remove debris/contamination)
• Repair crankshaft target/reluctor issues that prevent a usable CKP signal
• Address controller connector or input circuit faults only after external circuit verification

Can I Still Drive With P0335?

Driving with P0335 is not recommended because the Crankshaft Position Sensor “A” Circuit is critical for determining engine speed and position. If the circuit fault is intermittent, the engine may stall unexpectedly and may not restart, creating a safety and reliability risk. If the fault is hard (such as an open or short that prevents the controller from reading the CKP signal), the vehicle may crank and not start at all. If you must move the vehicle for safety, do so only if it is running smoothly and predictably, and avoid conditions where a sudden stall would be hazardous.

How Serious Is This Code?

P0335 should be treated as serious because the CKP “A” circuit is a primary engine management input. A failure can lead to immediate no-start or unexpected stalling, and it can also cause severe drivability problems if the signal becomes unreliable while driving. Even if the engine runs, the underlying circuit fault can worsen with heat, vibration, or moisture, turning an intermittent issue into a sudden failure. The correct approach is to diagnose and repair the circuit problem promptly and verify stable CKP signal operation afterward.

Common Misdiagnoses

A frequent misdiagnosis is replacing the crankshaft position sensor without verifying the Crankshaft Position Sensor “A” circuit (connector condition, wiring integrity, shorts, and power/ground where applicable). Another error is relying only on static resistance checks instead of performing voltage-drop and loaded tests during cranking, which can miss high-resistance faults. It is also a mistake to skip waveform verification; a scope check can quickly distinguish between a clean sensor output, a wiring-induced dropout, and an input-side problem. Finally, treating P0335 as a purely mechanical timing issue rather than a circuit fault can lead to unnecessary repairs.

Most Likely Fix

The most likely repair direction for P0335 is correcting an electrical fault in the Crankshaft Position Sensor “A” Circuit—such as repairing an open, short, high resistance, or poor terminal connection—so the controller can consistently receive and interpret the CKP signal. Only after the circuit is verified should component replacement or controller-side concerns be considered.

Repair Costs

Repair cost depends on whether the confirmed root cause is a sensor, wiring, connector issue, or control module problem. Verify the fault electrically before replacing parts.