Question - 2008 Pontiac G6 ECM

[Dennis Peacock]

My son's car has an engine light on. The local auto parts store says that the decoder says it's an ECM that has an issue. The local GM place wants about $800 to replace the ECM and reprogram. Do I have any cheaper alternatives? Please advise.

[Frederick Skelly]

Rockauto.com shows a remanufactured one for $175. But it says "local programming required", which Im guessing means you have to pay a GM dealer to load the software. I have no idea how much that runs. Link

[Bob Leistner]

Before you do anything, take the car to a reputable shop and have it properly diagnosed. ECM's don't go bad very often anymore and when they do, it is usually some sort of electrical problem that is damaging the ECM. I haven't needed to replace an ECM/PCM in quite a while. If something else is causing your problem, and you burn up a new one, you'll probably be on the hook for the second one.

[Matt Day]

For “older” cars like that, like mine which is an ‘04, and Bluetooth OBDII reader that uses a free app and your smart phone, is super handy. Mine cost $20 and has saved me time and money.

After I read a code I google it or check the car enthusiast forum for more information. For instance, mine was throwing a code for an O2 sensor, and after some searching I figured out which one, where it was located, what tool I needed, and a the exact part number I needed. I spent $100 on parts and the tool and saved probabaly $300 from not going to a shop.

[Paul Follett]

+1
very seldom will a ECM fail very seldom more likely a sensor wire or ground. The ECM is also very voltage sensitive so a weak battery or alternator that has a weak diode can also be an issue.

Before you do anything, take the car to a reputable shop and have it properly diagnosed. ECM's don't go bad very often anymore and when they do, it is usually some sort of electrical problem that is damaging the ECM. I haven't needed to replace an ECM/PCM in quite a while. If something else is causing your problem, and you burn up a new one, you'll probably be on the hook for the second one.

[Art Mann]

I agree with Bob and Paul. I worked on the design of engine and transmission controllers for Chrysler Motors and a European manufacturer for much of my career. There are many diagnostic features that are only available using an OEM analyzer. In most cases, it is possible to identify the actual circuit involved in the vehicle and the nature of the diagnostic failure. The little readout boxes that parts places and independent shops use are very limited in what they can do.