ECM repair being advised by service centres: Is it a scam?

Does the Ritz petrol (or any other car) have any known issue with its ECM that actually needs repair?

BHPian SS-Traveller recently shared this with other enthusiasts.

Yesterday. I received a somewhat frantic call from a friend in Ghaziabad, who drives a 2014 Maruti Ritz ZXi. His car had gone into limp mode - it starts but will not rev beyond ~1200 rpm. The car also had the CEL (Check Engine Light) glowing. He had taken the car to his 'trusted' friendly neighbourhood garage (FNG), who, without checking the DTC (Diagnostic Trouble Codes), advised him that the ECM itself is faulty, and will have to be taken to a specialist in Noida for repair, and will cost him Rs 4000 - because, apparently, "the Ritz has a known issue with its ECM, and needs to have the ECM repaired".

For the time being, my friend has parked the car back home without repairs, since he is travelling out of town tomorrow for an extended period, and did not want the headache of leaving the car at the FNG just in case the car did not run at all.

I am curious to know:

1. Is it common for FNGs or even authorized service centres (ASC) to 'repair' the ECM for any car? What is the usual amount they quote for such repairs?
2. Does the Ritz petrol (or any other car) have any known issue with its ECM that actually needs repair? If so, what is the problem, and what kind of repair is required?
3. What happened if you did allow the FNG / ASC to carry out 'repairs' of the ECM? Did that solve your problem, or did some other issue crop up, requiring further repairs and expenditure?
4. Big question: Is "ECM repair" a scam?

Here's what BHPian vishy76 had to say on the matter:

This is a known issue on some of the K12 engines. You can check out this video. The guy has also posted a similar video for the Swift 1.2. The symptoms he has stated are the exact same ones your friend is facing.

Repairing the ECM is an economical way since a brand new ECM would definitely cost 8-10X more. I have seen ECMs being repaired for Jettas and Passats (apart from the car shown in the video above) and the issue didn't recur after these repairs.

Repairing typically involves replacing a busted IC. Though the actual cost of the IC and labour isn't much, mechanics do have fat profit margins on these, simply because they also know the customer will still find it economical as compared to getting a new ECM altogether (and having to program it again).

To conclude, it definitely isn't a scam. Yes, an ECM failure is something that is difficult to diagnose and only a mechanic who has seen a couple or more on that specific make before will know the exact symptoms and figure it out. The rest might keep doing trial and error by replacing sensors and checking the wiring.

Here's what BHPian greenhorn had to say on the matter:

I would not take the term "ECM repair" at face value - a lot of FNG garages have an ECM specialist on call who has all the right tools, and anything that involves a visit from them is called an ECM repair. In this case, the Mech seems to have judged from past experience or hearsay from his field of work that this is something that is not going to end with just a scan, so probably is asking him to go visit a specialist directly

Even when my Indica had a wiring harness issue (which was diagnosed later -it manifested as a CEL which said a lot of expensive and usually reliable things were faulty) - My mechanic offered to troubleshoot it, but In his judgement said it was better if we took it to his ECM guy rather than try buying and changing things the ECM said was wrong.

The ECM guy took his time (and money) but ultimately identified it as a wiring harness loose connection issue which was a simple fix. I did not contest the estimate despite the simplicity of the fix because expertise and diagnosis were most of the cost of the fix, and it saved a lot of money compared to what the trial and error approach would have cost

Here's what BHPian SPIKE ARRESTOR had to say on the matter:

It would have been interesting to see the guy clear the DTC (at least try) using the tool before dismantling the ECU for "repair". I find it a bit difficult to believe they actually repaired the ECU.

My previous employer is a leading supplier of automotive control units. Our warranty team used to get control units from field, marked "Steuergeraet Defekt" (Control unit defective).

And what was the defect? -- In the majority of cases, the control unit had registered a DTC, with no hardware failure.

I hope that answers some questions.

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