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I've never had a failure Posted by Ari [Email] ![]() ![]() In Reply to: Average Life of an ECU?, Dave B 89 900s, Wed, 23 Oct 2002 18:31:00 Members do not see ads below this line. - Help Keep This Site Online - Signup |
There may have been some bad years, but I've never had an ECU failure, and that's with cars well over 12 years old and more than 150K miles.
ECUs do fail, but I suspect a decent amount that get replaced are perfectly fine. I've worked in aerospace electronics for a few decades, and most recently in aircraft/engine diagnostics. Even with highly trained personnel, the most common part to replace is the control box. After all, it's the one that reports the fault - it must be bad. Again, with highly trained personnel, only about 25%-35% of the control boxes that get returned to the factory for repair are bad. That means that close to 3 out of 4 times, the wrong part was pulled. Of course, that still give the ECU a bad name. In fact, the official reliability rate for the box takes a hit for those removals where nothing was wrong with the box. Life ain't fair.
OK, enough of that rant. What can you do to keep your ECU health? Heat, voltage, and troubleshooting. Heat kills electronics. There isn't a lot you can do about the underhood design, but make sure you don't block the grill, even (or especially) with extra coolers. Make sure the radiator fan works right, and it wouldn't hurt to put in a cooler fan thermoswitch. Underhood temps shoot up when the car is idling, so airflow is good.
What can you do about voltage spikes? Never reverse the polarity on your battery. Be very careful jumping batteries. For that reason, keep your battery in good shape, so you won't need a jump. Replace it before it goes dead. Keep your ground connections clean, and if the voltage regulator is getting tired, replace it.
Never plug in or unplug sensors with the power on. Period.
What's troubleshooting have to do with it? Well, since most box removals have nothing to do with the box, spend more time troubleshooting. Just because the ECU is easier to remove, don't. Make sure the connector is on tight. Make sure it really is the ECU. The connector issue is a big one with me. Connectors build up corrosion, or just need reseating. You can clean minor oxidation off the connector simply by unplugging it and plugging it back in. Of course, if you unplug an ECU and plug in a new ECU, and the problem goes away, you figure it was that the old ECU was bad. When if you had plugged it back in, it may have fixed the problem with no $$ invested.
The ECU should last the life of the car. Some will legitimately fail sooner. Most will live past the engine. To give you an idea, from what I've seen of car ECU's, they should have a MTBF (Mean Time Between Failures) of about 7500 hours. Just a guess based on parts count and type. If you assume that with driving on side streets, idling at lights, whatever, that you average 30 mph for the life of the car, that works out to 225K miles. Some will fail sooner, some later. And since that's just a guess on the MTBF it could be sooner. Of course, if one year had a particularly poor design, or a run of bad parts, some years could be a lot worse. But in general, they're pretty good.
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