Engine Control Module

The mechanic tells my daughter that her 2004 Mazda 3 (73k miles) needs a new engine control module – at a cost of $1500! (That includes the tow cost.) I had never heard the tern “engine control module.” Can you tell me what it is, how long it’s expected to last and if the cost should be this expensive?

Many thanks.

The engine control module is what controls the engines functions and monitors the emission controls. If the ECM does truely require replacement, this should be done at no charge to you. The EPA mandates that vehicle manufacturers must warranty the catalytic converters and engine control modules on their vehicles for 8 years/80,000 miles. It appears you fall within this warranty period.


Do as Tester suggest. The ECM is the computer that controls the engine.

I agree with the 2 previous responses. If you are in the USA, the ECM is covered by the federally-mandated warranty of 8 years/80,000 miles (perhaps longer in California.) Suggest she takes it to a Mazda dealer.

I agree. This car should be taken to a Mazda dealer.

Thank you so much!

Its called The Federal Emissions Performance Warranty which covers cats and engine control module for 8 years, 80,000 miles,some states more, here is the catch vehicle must have been properly maintained and must fail an emissions test that is approved by the EPA. Did your daughters car fail an emissions test?

There is also the Federal Emissions Defect Warranty,covers Air Induction,Fuel metering,Ignition,Exaust,PCV,EVAP,Emissions sensors,for a period of 2yrs 24,000,they must work as designed.

This info should be in the owners manual.

Whenever someone owns a reasonably new car, it always makes sense to re-read ALL of the vehicle’s various warranties (there are several, covering different systems on the car) before paying for any repairs. While I know that some people advocate always going to an independent mechanic, here we have an obvious case of a mechanic who was going to charge this woman $1,500. for something that is covered by her warranty.

Even if the mechanic was not sure whether or not this repair might be covered by the car’s warranty, if he was an honest mechanic, he would have told her to check with the dealership or–the most obvious course of action–to read her Owner’s Manual. Yes, I know that in this economy every business is trying to make money, but in this case, the mechanic would have been taking money out of this woman’s pocket under false pretenses.

While it is ultimately the responsibility of a car owner to read and familiarize himself/herself with the contents of the Owner’s Manual and the Maintenance Schedule (and although it is clear that the car’s owner did not do this), it would still be nice for her mechanic to do the right thing, rather than charging her for repairs that could be done free-of-charge by the dealership.

judyprius–I suggest that you and your daughter AVOID this mechanic in the future.

I quoted the Federal Performance Warranty out of one of my text books,the part that worries me is that it says the car “must fail an emissions test”

Here in AZ my 2004 isn’t tested,if my ECM failed would it be covered? I could see a case being made that my truck did not fail an emissions test. How is such a situation delt with? I have never seen a ECM or Cat replaced under the 8,80,000 for failing a test,plenty of 8,80,000 cats replaced for rattling (BMW E-39’s)

I “bumped” this one because i thought it was important enough to continue discussing (the must fail a EPA emission test prerequisite for ECM replacement)

The OP must take car to Dealer (as others have mentioned) Dealer must diagnois.

We never did get a answer as to what exactly is wrong with the ECM,does it have a “failure to communicate”? will the car run? does your state test?

I currently am at my dealership now and received a message on my phone about the ecm needing to be replaced. Still waiting for someone to come talk with me but I will let everyone know the process I go through to help others with the same problem in the future.

I am currently just over 50,000 miles. Well under the 80,000 miles mentioned.

Ok well mines under warranty so did not have to go anywhere as far as havibg it tested. Take it for what its worth.