Jeep Wrangler "Auto Start Stop" Warning Light Is On - Why?

The Electronic start-stop system of the Jeep Wrangler is primarily designed to cut your trips on the gas pump by deactivating the engine automatically to prevent long idling when the vehicle is not moving. Like when it's in a long queue under a red traffic light when the driver is waiting for the passengers, etc.

Stop start unavailable message highlights

• Common reasons:aux battery is dead, main battery is dying
• How to fix:check and charge the batteries, replace the faulty battery
• Possible consequences:if the batteries are dead, you may get stranded easily
• Priority level:Medium
• Can you drive?Yes
• DIY repair:Possible
• Repair price range:$200-$700

Start-stop in the Wrangler - what's this?

This is the feature that is used in your vehicle to stop the engine when it's not needed. It prevents your car from idling without any proper need for this. If you stop at a red traffic light and are going to be stopped for 1 minute, the auto start-stop system will turn the engine off.

Once you take your foot off the brake pedal, the engine will start automatically. This is a pretty straightforward way to economize some fuel. However, the primary goal of this function is to reduce the amount of emissions that your car emits into the atmosphere.

This function is important and it usually doesn't bother you much unless it starts malfunctioning. For example, you may get into a situation when your Wrangler will not start when needed. This is a stressful occasion and you need to quickly sort it out to avoid being an obstacle for other cars on the road.

Also, this is stressful for the battery of your car. Even though it's an EFB or AGM battery, it still has a limited number of times it can start the engine for only a short period of time.

Most Common Causes of the "Auto Start Stop" Warning Light in the Jeep Wrangler

In more ways than one, the "Auto Start Stop" Warning Light does not really do anything to your vehicle in terms of performance. If you're lucky enough, it might be gone the next time you restart your engine.

However, if it is always on or is intermittently popping up, it's possible that one of these is activating the light:

1. Battery Issues

This is the first thing you should check in your Wrangler. If you see the start-stop system warning which is the latter A encircled by an arrow and with an exclamation mark on the right side of it, this means that the system has to be serviced.

First of all, check the battery. If you have a simple start-stop system with just one battery in your car, check the voltage of the battery when starting the vehicle. Is it lower than 11.5 volts under load? You need a new battery. Be careful, Jeep vehicles with the start-stop system will only require AGM or EFB batteries, not just simple car batteries.

If your battery is over 4 years old, you may skip the check stage and just buy a new one. They don't usually live much longer than that.

Please remember that new Wranglers may have main and auxiliary batteries. Both can trigger this warning light and both need inspection when something goes wrong with the start-stop system.

Also, if you have a mild-hybrid system, you should check the second battery and its health. For this, we strongly recommend going to the Jeep dealership and having it inspected there.

2. Just inappropriate conditions

For your start-stop system to work well in the Jeep Wrangler, a set of conditions should be true. For example, the start-stop will not be working well if the battery voltage is low. We've discussed this above.

But a start-stop warning light may also pop up on the dash when the Wrangler spots a huge difference between the temperatures outside and inside the car. If the engine stops, the AC will stop working, too, because the compressor will be shut off. So, the Jeep may not turn off the engine if the AC is working and the outside temperature is high.

Or it may not shut off the engine if the engine temperature is low. In this case, it will keep idling till the temperature is optimal and only then the system will activate the start-stop function. Before this, you can see the start-stop warning light illuminating on the dash.

So, it's not always some serious problem or breakdown. Sometimes, the Wrangler shows this warning just to let you know that the auto start-stop is not available right now.

You may use the EVIC display to get more information about this warning light and why it is on.

3. Intelligent Battery Sensor Malfunction

If you have one of the fresh Wrangler models, you should know that it uses the IBS - Intelligent Battery Sensor. This is the battery management system that works with the main 12V battery and the auxiliary battery in your car. The sensor tells the start-stop system when the battery is OK or when it needs some more charging and the engine shouldn't be stopped.

This sensor may sometimes be faulty because of overheating or water damage. The problem is noticeable in the Jeep Wrangler 4xe.

In most cases, you may go to the dealership and they will replace or inspect the sensor under warranty. We haven't heard about any service bulletins yet but we are sure they will appear.

If the warranty is voided or over now, you may just buy the new sensor and install it. The job is not extremely complicated. And still, if you don't have any technical skills, you better find a mechanic who will do that for you.

4. Wiring Issues

When the "Auto Start Stop" warning light on the Jeep Wrangler's dash is illuminated, it may indicate that there is a problem with the wiring. Again, there are several ways to diagnose the causes of wiring issues using visual inspection and a multimeter.

We don't recommend digging in the Wrangler's wiring unless you have the proper experience and knowledge for that. It's important to check everything thoroughly for continuity and resistance. Also, corrosion on terminals and connections may lead to intermittent signals.

Checking the ground connection is also important. This one is known to have certain effects on the start-stop system in Jeep vehicles.

Unfortunately, everything that has something to do with the wiring should only be inspected and repaired by a trained person. Any mistakes in the process may lead to serious and expensive problems.

5. ECU Error

An ECU, or electronic control unit, is a type of computer that manages the engine in a vehicle. It regulates the air-to-fuel mixture and ignition timing to ensure optimal engine performance. The ECU also controls other systems in the vehicle having a certain impact on the start-stop system.

A problem with the ECU can cause the "Auto Start Stop" warning light or other types of alerts on the dash of the Jeep Wrangler. If there is a problem that may cause your engine to not start the next time after you stop it, the start-stop system will throw the warning on the dash and you will be able to drive.

Also, this may be a small glitch in the ECU or any other electronic control module. To deal with this, you may need to disconnect the 12V battery for 5-10 minutes and let the "brain" of the car calm down and forget all errors and problems. It may be that after you connect the battery, the vehicle will drive without any problems and the start-stop system will be active.

Can you drive with the Start Stop warning light?

Your Jeep Wrangler can perfectly drive without using the start-stop system. You may also deactivate it in the majority of models. But you shouldn't ignore the problem. If you see this warning light on the dash, it means that something is wrong unless it only tells you that the start-stop system may not be active due to weather conditions.

You should find the problem that doesn't allow the start-stop system to kick in. This may be a battery or a battery sensor, or maybe some issue with the software. It's important to locate and solve the problem because it may deteriorate and lead to other issues with your car.

Conclusion

The start-stop system in your Jeep Wrangler is important for fuel economy and emission control during city driving. We recommend keeping it activated at all times. But it's not uncommon for a Wrangler owner to see the warning light that tells them about the problem with this function.

When the start-stop system can't be activated due to weather conditions or AC settings, this warning light should be ignored. But in all other cases, it may be telling you about some serious problem that has to be addressed immediately.

If you can't locate the issue on your own, plan your visit to the Jeep dealership or to a good independent repair shop.