5 Symptoms of a Bad Crankshaft Position Sensor
Is your engine making strange noises, stalling, or not starting? Maybe your engine is jerking and you can feel it through your steering wheel? A faulty crankshaft position sensor could be to blame.
Here’s how to identify the most common symptoms of a bad crankshaft position sensor and how much it might cost to replace it. Tip: It will cost a lot less than ignoring it.
Crankshaft position sensors use magnetism to generate alternating current pulses as a pulse ring attached to the crankshaft rotates with each revolution of the crankshaft. The faster the engine’s crankshaft rotates, the more frequent these pulses will be. The vehicle’s ECM/PCM detects the frequency of these pulses and converts this feedback into an accurate speed.
Crankshaft position sensor feedback is essential to the proper operation of the engine as it can be used to accurately calculate the optimal timing of combustion per cylinder. Simply put, this feedback is used to determine exactly where the crankshaft is in rotation at any given moment while the engine is running.
Symptoms of a Bad Crankshaft Position Sensor
A faulty crankshaft position sensor in a vehicle is usually accompanied by one or more symptoms, some of which may negatively affect the vehicle’s drivability. The first sensible step in solving such an issue is often to focus on these underlying symptoms.
#1 – Illuminated Check Engine Light
A faulty crankshaft position sensor may or may not illuminate the vehicle’s Check Engine Light, depending on the situation and the vehicle model in question.
When the ECM or PCM detects an inconsistent or missing signal from the crankshaft position sensor, the Check Engine Light will illuminate to alert the driver.
There are a number of diagnostic trouble codes, including: B. P0335 and P0336. These are directly related to sensor feedback errors. Other related codes: P0016, P0017, P0018, P1345 (Crankshaft/Camshaft Position Sensor Correlation)
#2 – Stalling
Engine stalling is a common and potentially dangerous symptom of a failed crankshaft position sensor. This occurs because modern engines rely heavily on speed signal feedback to maintain efficient and continuous operation.
If the crankshaft position sensor does not provide accurate data about the engine’s speed and position, the ECM/PCM will not be able to properly adjust the timing of fuel injection and ignition events. The result may be a sudden loss of power and stalling of the engine, even while it is moving.
Stalling due to a failed crankshaft position sensor can be especially dangerous in heavy traffic conditions and when driving at high speeds. If your engine stalls repeatedly, it is important to have a mechanic check your vehicle as soon as possible.
#3 – Failure to Start
Another common symptom of a faulty crankshaft position sensor is the inability to start the vehicle’s engine. In this scenario, the engine will not start or run, even though the starter is clearly engaged. This typically occurs when no engine speed feedback is provided to the ECM/PCM within the first few seconds of cranking.
Without accurate information about the crankshaft position, the engine management system cannot determine the correct timing for fuel injection and ignition. The result is an engine that can continually start but will not start at all.
This can be especially frustrating for the driver because the problem only occurs intermittently; sometimes the engine will start successfully, and sometimes it will just refuse to start.
#4 – Poor Engine Performance
Assuming a vehicle with a faulty crankshaft position sensor manages to continue running, it is highly unlikely that its engine will be able to operate without a significant loss of efficiency. This is because accurate feedback of engine speed is essential for optimal combustion settings.
When the crankshaft position sensor provides inaccurate or erratic data, the ECM/PCM has difficulty precisely adjusting injection and ignition timing. This can result in a variety of performance issues, including rough idle, hesitation under acceleration, misfires, and an overall reduction in power.
Not only do these performance issues impact your driving experience, but if left unchecked for extended periods of time, they can also lead to increased wear on engine components.
#5 – Reduced Fuel Consumption
Reduced fuel economy is an often overlooked, but significant symptom of a faulty crankshaft position sensor. Because vehicle operational control relies on feedback from the engine speed signal, a failed crankshaft position sensor can result in fuel loss, as the ECM/PCM cannot properly adjust the timing of the combustion process in such a condition.
If the engine management system cannot accurately determine the crankshaft position, the engine will go into a “safety” mode, often resulting in a richer fuel mixture than necessary. This over-correction results in excessive fuel consumption and reduced efficiency.
While there are many factors that affect fuel economy, a sudden and sustained drop in MPG, especially when combined with other symptoms, may indicate a failed crankshaft position sensor.