EML light after long shut down. 'Engine fault: repair needed'.

I haven't used our C3 (110bhp Flair) since mid March. I started it and ran it for a few minutes about weeks ago with no issues. Last Thursday I decided to use it for a hospital trip as the brakes needed derusting. On starting it there was an alarm, EML on. On a restart the EML was still on, and an alarm on the screen 'Engine fault: repair needed'. So I called the local agents to book in for a diagnostic. The lady told me that they had had a lot of calls about a fault like this. This was' due to not being started for some time with the battery running low'. I was told to run it for a distance to recharge the battery and the alarm would go off. I certainly didn't believe that. So I drove to and from the hospital (20 miles each way), by which time the stop/start was working. But surprise surprise, the alarm is still comin on at each start.

So, anyone else having this issue? I'll be calling the agent again first thing tomorrow!

If your battery is low on charge, short of a very long trip it's unlikely the battery will regain a full charge just by driving the car. The electrical system of modern cars demand a lot of power from the alternator, not leaving a lot to charge the battery. You may regain the charge taken out of the battery by starting the car but that just puts you back to square one and only a partially charged battery. Then on top of that the electronics are very finicky about supply voltage. While "in the old days" you could get away with a partially charged battery 'cause all it did was start the car, you cant get away with it in modern cars.

If you take "the lady's" word for it, you would be best off having the battery fully charged by a mains charger.

While her explanation is plausible in your case, unless you read the code associated with the EML (or it goes out in the meantime) you will just be guessing anyway.

Ozvtr wrote: ↑Mon May 11, 2020 8:50 am If your battery is low on charge, short of a very long trip it's unlikely the battery will regain a full charge just by driving the car. The electrical system of modern cars demand a lot of power from the alternator, not leaving a lot to charge the battery. You may regain the charge taken out of the battery by starting the car but that just puts you back to square one and only a partially charged battery. Then on top of that the electronics are very finicky about supply voltage. While "in the old days" you could get away with a partially charged battery 'cause all it did was start the car, you cant get away with it in modern cars.

If you take "the lady's" word for it, you would be best off having the battery fully charged by a mains charger.

While her explanation is plausible in your case, unless you read the code associated with the EML (or it goes out in the meantime) you will just be guessing anyway.

As I wrote in the original post, the battery is sufficiently charged for the stop/start to work. As the car is under warranty, it's booked in for Friday, so they can read the codes and advise what is necessary. I will try to remember to post when I have more info.

It's been in today for diagnostics. It's the downstream oxygen sensor that has failed. I don't know what effect that will have on the engine. They said it would be £518 until I pointed out that it is under manufacturer's warranty. They can't get the part to early next week, but there is no issue leaving for a few days.

routemaster1 wrote: ↑Fri May 15, 2020 10:29 am I don't know what effect that will have on the engine.

The downstream O2 sensor only monitors the catalytic converter and does not effect the performance of the engine.

routemaster1 wrote: ↑Fri May 15, 2020 10:29 am They said it would be £518

WOW! If you walked around the corner to their spare parts division and bought a brand new genuine sensor it might cost up to 200 pound and that's an over inflated guess. An aftermarket might cost up to 100 pound (again, over inflated). The sensor is very accessible and would not take more than 15 minutes to change (although they would charge a minimum of 1 hour). 300 pound an hour labour charge? Where do I get a piece of that action? Just as well you don't have to pay it.

If got the car back, and it seems OK. Unusually for warranty work, they have given me paperwork.

To quote from the invoice. 'Carried out checks and found fault code P0138 and P0002 in engine ECU. Carried out further checks and found faults are related to downstream O2 sensor. Will require replacement sensor, autoadaptive reset and programming. Replaced sensor, autoadaptive reset and reprogrammed.

Costs : Labour £109.20, sensor £109.5, total £218.7. This was the price to the warranty. This would translate to £262 if VAT added. As I was originally quoted over £500 if I had to pay, it certainly looks like there is a huge mark-up for retail. Bearing this in mind, it certainly makes sense for me to take out their 3 year service plan, and to never let the car go out of warranty.