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Why Your Ford F-550 Check Engine Light Is On

The warning lights of car engine check, door opened, parked and hand break in the speedometer of a vehicleModern vehicles, including the Ford F-550, have an engine control module (ECM) that works with several sensors. When something goes wrong with the ECM or one of the sensors, the ECM sends a code and turns the check engine light on.

If your Ford F-550 has an illuminated check engine light, play it safe and shut the engine off immediately. Bring it to RDI Power in Brooksville, FL for Ford repair and maintenance.

How the ECM, Sensors, and Check Engine Light Interact

The ECM and the sensors work together. The sensors have two functions: 

  • send information to the ECM
  • adjust the air-and-fuel mixture and ignition timing

As long as the sensors send the information within the proper parameters and the ECM can use other sensors to adjust the engine, the check engine light will not turn on.

However, the computer sends a data trouble code (DTC) and illuminates the check engine light when: 

  • One of the sensors sends information that is out of range;
  • One of the sensors cannot correct a problem (like in a “rich” condition where there is too much unburned fuel in the exhaust).

If the ECM fails, it might not send codes. Or it might send several incorrect codes since the ECM cannot diagnose itself. 

Common Reasons for an Illuminated Check Engine Light

Some reasons the check engine light comes on in a Ford F-500 include:

1. Mass Airflow (MAF) Sensor

The MAF sensor measures the air that enters the engine. It tells the computer to adjust for the difference in altitude and humidity in the air. Common signs of a bad mass airflow sensor include rough idling, hard starting, or loss of power.

2. Loose Gas Cap

After filling up your Ford F-550, ensure the gas cap clicks a couple of times when tightening it. The gas cap seals the fuel system to help maintain the pressure required in the fuel tank. 

If you notice a check engine light right after filling up, make sure you don’t forget to put the cap on and make sure it’s tight. If that doesn’t solve the problem, you might need a new gas cap. 

While you can buy a new gas cap to see if the check engine light goes out, having an auto technician scan the vehicle for codes is better to ensure it’s not something else.

3. Aftermarket Items

Aftermarket parts and systems (such as alarm systems, exhaust parts, and aftermarket engine parts) often change the engine parameters. When the ECM cannot make the parameters go back between their limits, it sends a data trouble code and turns the check engine light on. 

If you recently installed an aftermarket system, it might be installed incorrectly. RDI Power can determine what the code is and, in many cases, reinstall the aftermarket system correctly. In some cases, you will not be able to use the aftermarket system.

4. Vacuum Leak

Vacuum leaks are common on all vehicles, not just the Ford F 550. 

The engine is a huge vacuum, sucking in air and fuel to make power. If one of the vacuum lines is compromised, the check engine light will come on as the ECM cannot compensate for the extra air entering the engine. 

Signs of a vacuum leak include misfiring, running rough, higher RPMs at an idle, random surging, or even a faint smell of fuel.

5. Oxygen Sensor

Generally, when the code is for an oxygen sensor that is out of range, it’s not the oxygen sensor itself that is bad. Something is causing too much or too little unburned fuel in the exhaust. It might be a bad plug, a bad wire or coil, a bad MAF sensor, or any other issues. 

A certified powertrain management technician at RDI Power will diagnose the vehicle to determine where the problem lies with your check engine light.

Contact RDI Power if Your Ford F-550 Has Check Engine Light Issues 

If your Ford F-550’s check engine light is on, contact RDI Power us for an appointment. Call us at (352) 433-3800 or request service via our website. You can also visit our shop, conveniently located at 1665 Donto Way, Brooksville, FL 34601.

 

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