Quick Answer: What Are The Symptoms Of A Bad ECU?

How do I know if my ECM relay is bad?

Symptoms of a Bad or Failing ECM-Power RelayNo power when the key is inserted.

One of the first symptoms of a problem with the ECM power relay is no power when the key is inserted.

Engine will not start.

Another common symptom of a problem with the ECM power relay is an engine that will not start or turn over.

Battery drain or dead battery..

How long does an ECU last?

100,000 milesThe engine control unit is a component that can last the lifetime of the vehicle, or develop issues after 100,000 miles. What causes them to fail is a bigger question. It typically comes from bad manufacturing, or some kind of electrical work done to the engine.

What problems can a faulty ECU cause?

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.

Can you drive a car with a bad ECU?

You absolutely cannot drive a car with a faulty ECU. While it may be functional for a while the potential for catastrophic failure does exist. If the ECU fails completely then your car is not drivable.

What does resetting the ECU do?

“Resetting the ECU” is the process of clearing all the long term memory from the ECU’s memory. These variables trim idle speed, fuel, spark, and more. The ECU will also store trouble codes for diagnostic capability.

Can a car run without a computer?

Yes, it’s true. Most cars prior to about 1980 had no computers in them at all. Carburetors and some forms of mechanical fuel injection operate without computer control – even though all modern cars use electronic fuel injection of some form, to my knowledge.

How do I reset my ECU?

To “reset” the ECU, all you have to do is remove the source of backup power. To keep the memory alive while the car is off, the ECU has a direct line, through a fuse, that goes right to the battery. This is usually the same line and fuse that supplies backup power to your radio so it doesn’t forget all of its settings.

Can ECM be repaired?

The first, and easiest, way to repair an ECM is if there’s a problem with the power supply. Oftentimes, these can be repaired by a skilled mechanic or electrician, by rectifying any shorts or bad connections. However, most ECM problems are a result of a bug in the software itself.

How much does an ECM cost to replace?

The cost for the new ECM will typically be around $800, with labor around $100, bringing the average total expense for an ECM replacement to approximately $900 before taxes and fees. This can increase depending on the shop you go to or the type of car you, running as high as $2,000.

How long does it take for a car computer to reset?

The readiness monitors will remain until the car has been driven long enough for the computer to evaluate the various system and sensors. The amount of time can vary based on the vehicle. In some cases it can take up to 100 miles for all of the computer monitors to completely reset.

How do you know if your ECU is bad?

These are the symptoms of a bad or failing engine control unit (ECU)Check Engine Light comes on. An illuminated Check Engine Light is one possible symptom of a problem with the ECU. … Engine stalling or misfiring. Another symptom of a bad or failing ECU is erratic engine behavior. … Engine performance issues. … Car not starting.

Does a used ECU need to be reprogrammed?

As long as the part is compatible it should be okay. I figure with all the “ecu” swapping going on around here I would of heard more about programming them if it was necessary. Thanks again!!! The ECU will dump the RAM side when disconnected from power, only keeping the ROM side in memory.