Finding Quick and Easy Temporary Fixes for Crankshaft Position Sensor Troubles

Your car’s crankshaft position sensor precisely measures the position of the crankshaft’s teeth and the engine’s rotational speed. This data is instantaneously transmitted to the car’s ECU as a pulsating voltage signal where each pulse directly corresponds to the tooth on the engine’s reluctor ring.

Your car’s ECU then uses this pulse data to adjust the timing of the spark delivered to each spark plug to optimize the internal combustion of the fuel/air mixture in each cylinder. The signal from the crankshaft position sensor also notifies the ECU if any of the cylinders are misfiring or are otherwise performing out of the norm.

This also means that a fault in a crankshaft position sensor or a sensor that sends intermittent data will also dramatically affect engine performance. Usually, the ECU will turn the check engine light on, demanding that you pull over to the side of the road.

If you’re lucky, you might be able to pull over in a gas station parking lot or perhaps even make it back to your own driveway. This will give you more time to troubleshoot what’s wrong with the crankshaft position sensor and possibly pull off a quick fix.

What Are Common Symptoms of a Bad Crankshaft Position Sensor?

Sometimes the symptoms of a bad crankshaft position sensor start out subtle, like a rough idle, poor MPG, or the engine feeling down on power. Though there are certainly other symptoms like stalling out or This is linked to the ECU not having the correct information it needs to precisely synch the delivery of fuel and spark to the cylinders.

1. An Increasingly Rough Idle

When the crankshaft position sensor first starts to fail, minor incongruities in the timing of the engine will give the car a rough idle. As it worsens, you’ll experience worsening engine vibrations that feel like a series of small misfires. This is more likely to happen when you’re sitting at a red light with the engine running hot. You might also notice it when you step down hard to accelerate up to highway speed.

2. Poor MPG

Poor fuel injector performance caused by a failing crankshaft position sensor can leave unburned fuel in the cylinders, which has a cumulative effect on your engine’s fuel consumption. If the sensor is just starting to fail, your MPG rating might slowly dip a little. As it worsens, the engine’s fuel efficiency will take a nosedive.

The added problem is that when unburned fuel enters the exhaust system, it can also cause problems with the catalytic converter. This can gradually cause it to clog, damage the exhaust system, and produce foul-smelling exhaust with strange fuel vapors.

3. Foul Smelling Exhaust

The unburned fuel caused by a failing crankshaft position sensor can travel into the exhaust system causing foul-smelling exhaust. The odors might be reminiscent of sulfur or rotten eggs, or it might smell immediately of evaporating gasoline.

4. Frequent Stalling

The timing problems caused by failing crankshaft position sensors will often cause random stalling events. The engine tends to die at the worst possible moments, like when you’re accelerating hard to merge up to highway speed.

5. Inconsistent Acceleration

Inconsistent acceleration often indicates that a failing crankshaft position sensor is sending intermittent data. The engine bogs down at times, then suddenly, the ECU gets the data it needs to get the timing right, and the engine suddenly bursts to life. This is a symptom of a bad crankshaft position sensor that typically happens in tandem with random stalling problems.

6. Engine Misfires

The inconsistencies in fuel injector and spark plug performance caused by a bad crankshaft position sensor can lead to recurring misfires. You’ll often notice it first when you need to step down hard on the accelerator. Though it can easily worsen into misfires and rough idling that kills the engine when you’re sitting at a red light.

7. Hard Starting or Non-Starting Engine

As a crankshaft position sensor goes from failing to bad, the engine will be hard to start or might not start at all. This is due to a severe imbalance between the timing of the fuel delivery and the spark. Then, you end up with a flooded engine that has too much-unburned fuel and timing problems to start the engine. If you’re lucky, you might be able to let it sit for a solid 15 to 20 minutes, and it might restart again.

8. Check Engine Light

A failing crankshaft position sensor will eventually cause the check engine light to come on. It might only flash when the engine misfires or stalls. Sometimes, the light will simply stay on. Whichever is the case, the ECU will then store a code that will help you confirm that it is indeed a bad crankshaft position sensor and not some other engine fault.

Where Is the Crankshaft Position Sensor Located?

If you want to visually inspect the crankshaft position sensor and/or check for any loose wires, you can usually find it on the front underside of the engine. It looks like a little plug right next to the engine’s reluctor ring.

Some are held in place with a locking tab, though some models might use fastener hardware. Before you pull it out, take a minute to make sure the wires aren’t loose or showing signs of shorting out. It’s entirely possible for the sensor to be still good, but damaged wiring is preventing the voltage pulses from reaching the ECU.

Inspecting the Crankshaft Position Sensor

Once you feel confident that it isn’t the wiring isn’t the problem, you can release it for a visual inspection. Pay attention to any fasteners and/or locking clips.

Once you have the crankshaft position sensor out, look it over for any signs of contamination from oil or engine bay debris. Then, test it with a multimeter or voltmeter to determine if it’s bad.

Quick Fix for a Bad Crankshaft Position Sensor

In a pinch, you might be able to reset the crankshaft position sensor to get you back on the road again. Sometimes the sensor can start to fail or have a problem due to excessive vibration and heat in the engine bay without technically being fouled.

Crankshaft Position Sensor Quick Fix #1: Wait and Restart the Car

Shut the engine off, and disconnect the negative (Black) and positive (Red) leads in that order. Let the car sit for at least 10 minutes to let the engine cool and any lingering electricity to dissipate. This is the engine sensor equivalent of unplugging your computer and plugging it back in again.

When reconnecting the battery, make sure to do the leads in reverse odor. You want to put the positive (Red)) lead on first and then the negative (Black). Then, leave all your other electrical accessories off while restarting the engine.

It’s okay if the engine runs a little rough for the first minute or two after restarting, as there might still be unburned fuel or other minor faults in it.

Crankshaft Position Sensor Quick Fix #2: Pull the Sensor & Start the Engine

In some older models, you might be able to pull the crankshaft position sensor and still get the engine to start on its own. It will run rough, but in an emergency, it might get you far enough down the road to pull over into a safe parking lot somewhere.

Crankshaft Position Sensor Quick Fix #3: Relearn the Sensor

Let’s say you pulled out the crankshaft position sensor and it was dirty from something like an accidental stray droplet of oil the last time you checked your dipstick. You give it a good cleaning and you want to reinstall it.

In a newer vehicle, this might require treating the old sensor like you’re installing a new one. Using a tablet with an ECU connection, you might be able to relearn the crankshaft position sensor to restore communication between it and the ECU.

The Cost to Replace a Crankshaft Position Sensor

Even if you get one of the quick fixes to work, chances are good that your crankshaft position sensor needs to be replaced sooner rather than later. If you’re a modestly capable DIY mechanic, you can probably do this yourself to save $100 or so in mechanics fees.

The part cost for a new crankshaft position sensor typically ranges from $25 to $55.

It will take you around an hour to physically remove and install a new one. However, you might need to relearn the crankshaft position sensor as well.

If you’re uncomfortable with this or don’t have the tech to relearn your sensor, a mechanic can usually replace the bad crankshaft position sensor for an extra $100 to $125 in labor cost.

Frequently Asked Questions

Will a Bad Crankshaft Position Sensor Activate Limp Home Mode?

If your car has this feature, a bad crankshaft position sensor can trigger limp home mode. This will limit the rev range and transmission gears to create safe driving conditions. You can usually deactivate limp home mode by turning the engine off and disconnecting the battery for 5 to 10 minutes, though this might not be wise.

Can you drive with a bad crankshaft position sensor?

Sometimes, you can still drive with a crankshaft position sensor that’s just started to fail. The rough idling, poor MPG, and hard starts are usually annoying but won’t usually leave you stranded. It’s when you start suffering inconsistent acceleration issues; the engine starts stalling, or misfires that you risk serious engine damage and safety problems that make it a bad idea to drive with a failing crankshaft position sensor. 

How Long Does a Crankshaft Position Sensor Last?

Automakers design crankshaft position sensors to last around 100,000 miles. However, they can certainly fail sooner than that. Especially if your engine has been running hot and you get stuck in a lot of stop-and-go traffic. Poor maintenance habits can also lead to premature death.

Conclusion

If your crankshaft position sensor is starting to fail due to dirt, corrosion, or excessive heat in the engine bay, you might be able to pull off a quick fix reset. This is as simple as turning off the engine, disconnecting the battery, and waiting for 10 minutes before restarting the car.

If you have a tablet and the tech to connect to the ECU, you might be able to pull the sensor, give it a good cleaning, and then relearn the crankshaft position sensor to synch it up again.

Just bear in mind that these are quick fixes to get you back on the road long enough to get home or get the car to your mechanic. Once a crankshaft position sensor starts to fail, it inevitably will need to be replaced before you can trust the car to be truly safe to drive again. Attempting to push it and drive on a bad crankshaft position sensor risks causing some serious damage.