Troubleshooting Guide: Jeep Wrangler Check Engine Light, No Codes

Check engine light on a Jeep Wrangler flashes or stays on when there is something wrong that requires attention. Sometimes the dashboard also shows codes that indicate a particular problem that needs to be fixed. But other times no codes are flashing which makes it harder to diagnose.

Even without any codes flashing you can properly diagnose the exact issue with your Jeep Wrangler by following the proper guidelines. Check for the common issues that cause the problem of check engine light such as loose gas cap, spark plugs, MAF sensor, air filters, and so on according to the guidelines provided below to fix the issue.

Other times there can be nothing wrong in particular with your Jeep Wrangler and the check engine light can still be flashing and will require resetting the light which will also be discussed below.

Why Jeep Wrangler’s Check Engine Light Is on but No Error Codes Show?

Various reasons can be behind the issue of the check engine light staying on but no error codes showing on the Jeep Wrangler such as a loose gas cap, malfunctioning spark plugs, faulty sensors, dirty air filter, and so on. These issues can trigger the engine light but the dashboard might fail to show any particular error codes.

How to Diagnose a Check Engine Light Without Error Codes?

There are two methods of diagnosis to get error codes if your Jeep Wrangler is showing the check engine light without any codes. The first method is by using the ignition and the second is by connecting an OBD 2 scanner to your car.

You can check for error codes on your Jeep Wrangler if it keeps flashing the check engine light without showing any error codes. Insert the key into the ignition and turn it three times to the run position without starting the car. This will trigger the On-Board Diagnostics or the OBD computer which will then show the exact error code on the dashboard.

The second method is attaching a separate OBD2 sensor to your car. OBD2 sensors will automatically scan the entire car for problems and show respective error codes for the issues. OBD2 scanners cost about $30 to $200. Most workshops will provide this service for free.  

What Causes Check Engine Light on With No Codes?

Various components work together to operate the vehicle and issues in any one of them can trigger the check engine light. The most common and frequent reasons that create the issue of check engine light are discussed below with potential solutions. 

Loose Gas Cap

One of the most common reasons for check engine light flashing on the dashboard is a loose fuel cap. The fuel cap prevents the gasoline fumes from leaving the tank which is crucial to maintain pressure in the system.

The signs of a faulty gas cap are the cap failing to close properly, check engine light flashing after filling the fuel tank, and dust and debris accumulating around the fuel cap. Fuel caps can get broken or damaged naturally due to time and usage or because of broken seals and gaskets.

Solution: Tighten the gas cap properly after refilling the fuel tank. Replace the broken gasket and the cap with new replacement parts to solve this issue. A new replacement fuel cap will cost somewhere between $20 and $100.

Malfunctioning Spark Plug

Spark plug malfunction can also trigger the check engine light without showing any codes. Spark plugs play a vital role in the engine by providing the necessary flicker to start the combustion process in the cylinder.

Symptoms of malfunctioning spark include misfiring of the engine, engine failing to start, rough idle, engine surging, high fuel consumption, lack of acceleration, and so on.

Solution: Check the spark plugs and the spark plug wirings carefully to find out if they are functioning properly. Wipe the spark plug with a cloth if there is carbon accumulation on the electrodes.

Make sure that the electrodes are functioning properly and the gap between them is in the correct order. Fix the gap if it becomes too wide or narrow. Replace the spark plug entirely if it gets beyond repair. Spare spark plugs will cost $15-$35 a piece.

Mass Air Flow Sensor

Another reason why the check engine light might be on is because of a faulty Mass Air Flow or MAF sensor. MAF sensor is responsible for detecting the airflow in the engine and sending this to the Engine Controle Module which determines the airflow based on the readings.

A faulty MAF sensor will show various symptoms like the engine idling, failing to start, engine stalling, excessive jerking, engine stuttering, and so on.

Solution: Check your Jeep Wrangler with an OBD2 scanner to be sure that the issues are occurring due to a faulty MAF sensor. OBD2 scanner will show P0101 if there is a faulty MAF sensor.

Replace the old MAF sensor with a new one to resolve this issue. A new MAF sensor for your Jeep Wrangler will cost about $20-$90.

Clogged Air Filter

A clogged air filter is another reason that can trigger the check engine light on your Jeep Wrangler. Air filters filter out all the dust and other unwanted substances from the air and supply it to the engine manifold so that fuel can be burned with clean air.

Symptoms of a clogged air filter include weird noises, check engine light, black smoke from the exhaust, noticeable reduction in fuel economy, hesitation or stumbling on acceleration, and so on.

Solution: Regularly check your air filter and keep it clean. Replace the air filters entirely if they become too dirty and clogged. A spare air filter for your Jeep Wrangler will cost about $15-$40.

Faulty Catalytic Converter

Check engine light can also flash because of a faulty catalytic converter. The catalytic converter is a vital component of the car as it filters out various harmful pollutants exhausted by the car and keeps the environment safe.

Signs of a faulty catalytic converter include sluggish engine performance, reduced acceleration, rotten egg smell coming from the exhaust, black smoke, extreme heat coming from under the vehicle, and so on.

Solution: Replacing the faulty catalytic converter with a new one is the only effective solution for this problem. A spare catalytic converter will cost about $150-$300.

Malfunctioning Oxygen Sensor

The oxygen sensor detects the level of oxygen in the engine and sends the data to the ECM which takes action accordingly. A faulty oxygen sensor can also trigger the check engine light in the Jeep Wrangler.

Other symptoms of a faulty oxygen sensor include engine misfiring, rough idling, stalling, engine stalling, overheating, reduced fuel economy, black smoke from the exhaust pipe, and so on.

Solution: Replace the faulty oxygen sensor with a new one which will cost about $40-$80.

Faulty Fuel Injectors

Faulty fuel injectors can also keep the check engine light turned on. Fuel injectors inject the mixture of fuel and air into the engine manifold to start the combustion process. 

Symptoms of faulty fuel injectors are engine misfiring, engine stalling, rough idling, car failing to start, fuel economy going down, leaking fuel, and so on.

Solution: Replace the malfunctioning fuel injector with a spare part. It will cost about $40-$90 for a spare fuel injector.

Low Oil Level

Engine oil helps to keep all the moving components inside the engine lubricated so that they avoid excessive friction. A low oil level can also trigger the check engine light which might not show any error codes.

Other symptoms of low oil levels in the engine include an illuminated oil pressure warning light, a burning oil smell, knocking or clunking noises, engine overheating, sluggish vehicle performance, poor fuel economy, engine stalling, and so on.

Solution: Check the oil level regularly with the dipstick and refill to the desired level. Change oil on a regular basis to keep your car in pristine condition.

Malfunctioning Vacuum Hoses

Malfunctioning vacuum hoses can also trigger the check engine light as the sensors inside the engine detect unwanted airflows and send that data to the ECM. Other symptoms of leaking vacuum hoses include engine performance issues, erratic RPM, and, hissing or suction noises. 

Solution: Leaking vacuum hoses are notoriously difficult to fix on your own and will require professional care. Take your Jeep Wrangler to a trusted workshop if such a problem occurs. 

Faulty Throttle Position Sensor

The throttle position sensor tracks the position of the throttle and sends the data to the ECM. A malfunctioning throttle position sensor can also trigger the check engine light. Other symptoms include unwanted jerking of the vehicle, sudden idle surges, engine stalling, hesitation during acceleration, sudden surges in speed, difficulties in changing gears, and a drop in fuel economy.

Solution: Replace the throttle position sensor with a new spare part to resolve this issue. A spare throttle position sensor for your Jeep Wrangler will cost about $15-$50.

Causes Check Engine Light on With No Codes

Will the Jeep Wrangler Check Engine Light Reset Itself?

Sometimes, the check engine light resets by itself without any outside interference but other times it indicates that there is something wrong with the car that requires maintenance.

How to Reset Jeep Wrangler Check Engine Light?

The steps to reset the check engine light of the Jeep Wrangler are given below.

Step 1: Pop the hood and locate the battery.

Step 2: Disconnect the negative cable from the battery terminal.

Step 3: Wait about 20 minutes.

Step 4: Reconnect the negative cable to the battery.

This should reset all the warning lights unless something is actually at fault and needs to be fixed.

How Much Does It Cost to Get the Engine Light Problem Fix?

The cost to get the check engine light flashing problem depends on what component needs to be fixed or replaced and the cost of labor in your area. It can cost about $20 to $1000 to fix the check engine light problem depending on the severity of the issue.

How to Prevent Jeep Wrangler Check Engine Light Problem?

You can prevent the check engine light problem with regular care and maintenance. Regularly check the engine oil level and keep it full. Ensure that the gas cap, gaskets, seals, and hoses are properly sealed and have not sprung a leak.

Is It Safe to Drive Your Jeep Wrangler With the Check Engine Light On?

Yes, it is relatively safe to drive your Jeep Wrangler with the check engine light on but it should be fixed as soon as possible.

How Many Miles Can You Drive With the Check Engine Light?

It is recommended that you do not drive more than 50 to 100 miles with check engine light on as it can pose a great danger to both the vehicle and the driver.

Leave a Comment