How to Tell If You Have a Faulty ECU

The ECU, or engine control unit, is a major component of your car's onboard computer. It's used to regulate many systems and subsystems in your car's engine, drive train and other major components. There are many symptoms that can be associated with a faulty ECU. Here are some ways to tell if yours is damaged or faulty.

The Check Engine Light Is On

If you vehicle's check engine light remains on constantly, and never goes off, there's a good chance that your vehicle has a faulty engine control unit. There are numerous reasons why a car's check engine light will remain on. The most common reason is a problem with the ECU. If you notice that your check engine light is always on, take your in vehicle in for service and request that they check the engine control unit.

The Car Won't Start

If your vehicle fails to start for no apparent reason, this is also a good indicator that there may be a problem with the ECU. If you check the car battery, starter and other common electrical components, and the vehicle still does not start, a faulty engine control unit should be the next logical thing to consider.

Other Common Symptoms

Many other symptoms can be associated with a faulty ECU. For example, poor performance or unexplained drops in fuel economy or efficiency are often related to onboard car computer problems, or faulty ECU issues.

A damaged ECU can cause problems when shifting gears in an automatic transmission, or cause sudden jerking or stopping that's similar to transmission problems. If you experience jerking or stopping, you regularly maintain your transmission properly, and the vehicle has adequate levels of transmission fluid, then a faulty ECU should be suspect.

ECU Computer Diagnostics

If you suspect that the electronic control unit in your vehicle is damaged, or is going bad, you should immediately take your vehicle to the nearest dealership, repair shop or service center. When choosing a service center to check for a faulty ECU, make sure that you visit one that uses the latest computer diagnostic equipment for checking your car's onboard computer.

While there are many excellent repair shops and service centers that have the required equipment to diagnose a faulty ECU, if you want to be absolutely certain that your car is correctly diagnosed, consider taking your vehicle to a dealership that sells your particular vehicle. By visiting an authorized dealership, you will always be assured that the equipment used to diagnose it provides the most accurate readings and results. This will help the mechanic or technician best repair your vehicle.

How Much Should You Pay for ECU Repairs?

ECU repairs can be very expensive. The part alone can cost between $1,000 and $3,000, depending on the make and model of your vehicle. Fortunately, an ECU can be repaired or reprogrammed in many cases—thus preventing the need to actually replace an ECU.

Average Cost at a Garage

You should expect to pay between $150 and $300 at a local repair shop or service center just to have the ECU inspected and tested. In many cases, the faulty ECU can be repaired or reprogrammed, and this type of repair will usually run between $300 to $750, depending on the make and model of your vehicle. In the unfortunate event that you need to actually replace the ECU, you should add about $500 to $600 to the cost of the part for labor to install and program the new ECU.

Online Repair Services

These days, there are many online companies that provide ECU repair services also. These companies allow you to send your faulty ECU to their location for repair. They do the work and then ship it back to you. For many models of vehicles you can find online repair services for between $300 and $400 for a complete repair or reprogram of the ECU. However, there are service providers that auction their services on sites like eBay that can perform the work for as little as $50.