What code will a bad crankshaft sensor cause?
A bad crankshaft position sensor (CKP) most commonly triggers P0335–P0338, which relate to the CKP A circuit, and, on some engines with a second CKP sensor, related P0339 and CKP B codes. Exact codes can vary by vehicle make and model.
The crankshaft position sensor provides timing information to the engine control unit. When the signal is lost, intermittent, or out of spec, the ECU can set DTCs, potentially affecting starting, idle, and power delivery. This article explains the codes you may encounter, what they mean, and how to approach diagnosis and repair.
Common CKP codes
CKP A circuit codes explained
The following codes are the primary ones you’ll see for a malfunctioning CKP A circuit. They indicate issues with the sensor circuit, its signal, or related wiring.
- P0335 – Crankshaft Position Sensor A Circuit Malfunction
- P0336 – Crankshaft Position Sensor A Circuit Range/Performance
- P0337 – Crankshaft Position Sensor A Circuit Low Input
- P0338 – Crankshaft Position Sensor A Circuit High Input
These codes broadly point to problems in the CKP A wiring, connector, sensor, or reluctor signal. Dirt, damaged connectors, corroded pins, a damaged reluctor wheel, or a failing sensor are common culprits.
CKP B circuit codes (if your vehicle uses a second CKP sensor)
Notes on multi-sensor configurations
Some engines use a second crankshaft position sensor or have an alternate circuit labeled B. In those cases, the following codes may appear. Exact codes can vary by manufacturer.
- P0339 – Crankshaft Position Sensor B Circuit Malfunction
- P033A – Crankshaft Position Sensor B Circuit Range/Performance
- P033B – Crankshaft Position Sensor B Low Input
- P033C – Crankshaft Position Sensor B High Input
Because not all engines have a CKP B sensor, some vehicles will not produce these codes. When they do appear, the diagnostic approach—checking wiring, connectors, sensor, and reluctor—remains similar to the CKP A circuit.
Common symptoms that accompany CKP codes
What drivers might notice
Beyond the DTCs, a failing CKP sensor can produce several drivability issues. Typical symptoms include:
- Engine cranks but won’t start, or intermittent starting problems
- Engine stalls or hesitates, especially at idle or during acceleration
- Rough idle or misfires
- Check Engine Light illuminated with CKP-related codes
- Reduced power or poor throttle response
Symptoms can vary by vehicle, and other sensors can sometimes mimic CKP problems. A proper diagnostic approach is essential before replacing parts.
Diagnostic steps and what to do next
Approach and tools you'll need
To diagnose CKP-related codes, use a scan tool to read DTCs and, if possible, monitor the CKP signal live while cranking and running. The following steps are commonly recommended:
- Verify the codes and re-scan to confirm they reappear after clearing.
- Inspect CKP wiring and connectors for wear, damage, corrosion, or loose pins; ensure proper grounding.
- Inspect the reluctor wheel (tone wheel) and its mounting for damage or missing teeth.
- Test the CKP sensor's resistance and, if available, its output waveform with an oscilloscope or a reputable multimeter test method.
- Replace the CKP sensor if electrical tests show out-of-spec values or if the sensor is physically damaged.
- Clear codes and test drive to confirm the issue is resolved and codes do not reappear.
Following these diagnostics helps avoid unnecessary replacements and ensures you address the actual fault in the CKP system.
Summary
When a crankshaft position sensor fails, you most commonly see CKP A circuit codes P0335–P0338. If your vehicle uses a second CKP sensor, you may also encounter CKP B codes such as P0339 and P033A–P033C, with exact codes depending on the make and model. Diagnosing these codes involves checking wiring, connectors, sensor integrity, and the tone/reluctor wheel, often using live data or an oscilloscope to verify a clean CKP signal. Addressing the root cause—whether a damaged sensor, wiring fault, or mechanical issue—typically resolves the codes and restores normal starting and running.
Will a bad crankshaft sensor throw a code?
Yes, a bad crankshaft sensor will almost always throw a check engine light and set a diagnostic trouble code (DTC), such as P0335, because the vehicle's computer monitors its performance. However, there are some cases where it might fail without a code, such as if the issue is with the "tone ring" the sensor reads rather than the sensor itself, or if the code is not read immediately.
Common codes for a bad crankshaft sensor
- P0335: Crankshaft Position Sensor "A" Circuit Malfunction. This is often the most common code and can be caused by a bad sensor, damaged wiring, or a poor connection.
- P0336: Crankshaft Position Sensor "A" Circuit Range/Performance. This can indicate issues with the sensor's accuracy or responsiveness.
- P0337: Crankshaft Position Sensor "A" Circuit Low Input. This often points to a problem with the wiring of the sensor.
Why a code might not appear
- Damaged tone ring: The sensor reads a toothed disc called a tone ring on the end of the crankshaft. If this ring is damaged, covered in sludge, or installed incorrectly, the sensor may not be able to read it properly, leading to a no-start or misfire without a code, as the tone ring itself isn't directly monitored by the computer, JustAnswer.
- Wiring issues: While a short or open circuit will typically cause a code, subtle wiring problems could manifest without one.
- Timing is off: If the timing belt or chain has jumped a tooth, it can disrupt the signal, but it may not immediately throw a specific sensor code, Quora.
- Code not yet detected: A car's computer might not have detected the fault yet, even if symptoms are present, 1A Auto.
What to do if you suspect a bad sensor
- Scan for codes: Use an OBD-II scanner to check for any trouble codes, AutoZone.com.
- Check symptoms: Look for symptoms like the check engine light, stalling, hard starting, poor acceleration, and rough idling, AutoZone.com.
- Consult a mechanic: If you are unsure about the diagnosis, a professional mechanic can accurately diagnose the issue.
What code pops up for a crankshaft sensor?
A common crankshaft position sensor code is P0335, which means "Crankshaft Position Sensor 'A' Circuit Malfunction". This code indicates the engine control module is not receiving a signal from the sensor, which is vital for engine timing, fuel injection, and spark plug firing. Other related codes, such as P0336 (Circuit Range/Performance) or P0339 (Circuit Intermittent), may appear as well. Symptoms can include a check engine light, stalling, hard starting, or engine misfires.
This video explains the P0335 code and its causes: 1mMechanical BoostYouTube · Oct 14, 2024
What the code means
- P0335: The primary code for a general malfunction in the crankshaft position sensor's 'A' circuit.
- P0336: The signal from the sensor is outside of the expected range or performance specifications.
- P0339: The signal from the sensor is intermittent, meaning it comes and goes.
Common causes
- A faulty or failing crankshaft position sensor
- Wiring issues, such as broken, frayed, or loose wires
- A bad electrical connection at the sensor's connector
- A problem with the reluctor ring (also called a tone ring), which the sensor reads
- Engine oil contamination on the sensor
- A malfunctioning engine control module (ECM or PCM)
- A weak or dead battery, or starter motor issues
- A broken timing belt or chain that has thrown off engine timing
This video explains the possible causes of the P0335 code: 55sEasyAutoFixYouTube · May 11, 2024
Symptoms
- Check engine light is on
- Engine won't start: or takes a long time to start
- Engine stalls: unexpectedly
- Engine misfires
- Hesitation during acceleration
What are the symptoms of a failing crank sensor?
Symptoms of a failing crank sensor include the Check Engine light coming on, difficulty starting or engine stalling, rough idling, engine misfires, and poor acceleration. A failing sensor can also lead to reduced gas mileage and unusual vibrations.
Performance and starting issues
- Difficulty starting: The engine may crank but not start, or it may take longer than usual to start.
- Stalling: The engine can stall while driving, often without warning, which can be a safety risk.
- Rough idling: The engine may run or vibrate unevenly when idling, such as at a red light.
- Misfires: The engine may feel like it is stumbling or shaking, especially under load.
- Poor acceleration: The vehicle may hesitate or feel sluggish when you press the accelerator.
Other symptoms
- Check Engine light: The dashboard warning light will often turn on when the sensor is failing.
- Reduced fuel efficiency: Incorrect fuel injection timing can cause the vehicle to use more gas.
- Increased vibrations: The engine may shake more than usual, particularly at idle or during acceleration.
What to do
- If you experience these symptoms, it is recommended to have your vehicle inspected by a qualified mechanic. A failing crank sensor can cause further damage if not addressed, says the YouTube video from Christians Brothers Automotive and CarParts.com.
How serious is a P0335 code?
Driving with the P0335 error code is not recommended because it can cause your vehicle to stall unexpectedly or fail to start. A malfunctioning crankshaft position sensor can also lead to misfires or poor fuel economy, potentially damaging the engine over time.
