My stalling PHEV: P10DC / EV System Service Required

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richi

Member
Joined
Nov 10, 2016
Messages
22
Location
Sherfield-on-Loddon, UK
Hello gang. Here's the saga of my "stalling" PHEV. Posting here in the hope that someone has a smart suggestion. Here's the briefest summary I can muster:

From a stone-cold start, when the ECU first calls for the engine to turn, it runs for 25 seconds then stops, displaying EV System Service Required. A DTC is stored: P10DC, which appears to be generic.

Video: https://www.youtube.com/watch?v=P9Qaw3Qk1D8

After switching off then on again, engine operation is OK for the rest of the day. Even after being parked for several hours it's OK. The problem only re-occurs the next morning.

Problem began when the weather turned cold, on October 23. Vehicle is outdoors, not garaged.

Much head-scratching at Brighton Mitsubishi last week. Huge thanks to David Evans and Kevin. They retrieved three other DTCs: B1115, C1776 and C1753. The first makes no sense, because there's no issue with the cabin heating. It appears the other two are thrown because the ACC/FCM system sees the P10DC code.

Brighton Mitsubishi consulted MMCUK on Friday and was told it could be a fuel-contamination issue. But we don't think this theory fits the behaviour: engine is fine while driving in series and parallel modes (Brighton also did an extensive test drive).

Because I can't demonstrate the problem until after an overnight cold-soak, we didn't get any further, but we've eliminated the main engine relay (they substituted a known-good spare).

Because the problem began when weather was cold and damp, it seems like an ignition issue, so I investigated the coils. I've sprayed GT85 as a damp repellent over the area, but with no luck.

Otherwise, because it always stops 25 seconds into the initial fast-idle, it seems like the ECU is objecting to something a sensor is telling it. But I'd love to know why there's no DTC to say which sensor!
 
This morning's test was to use the 10-second-CHRG button trick to start the engine: It stalled just the same, after 25 seconds. So we've eliminated the heater as cause.

Here's the interesting thing: After it stalled, I tried again and it stalled again after 25 seconds. I've never seen it do it twice in a row. But it is freezing this morning—the coldest it's been since the saga started. (It ran fine the 3rd time.)

So perhaps it would have been fine if starting the engine using the heating, due to the extra warmth going into in the coolant. Tomorrow's test will be after a 30-minute pre-heat. I did this one day last week and there was no stall, but need to repeat it a few times to be sure.
 
Update: The underlying issue was that a dealer had screwed up the spark-plug/ECU recall.

The recall requires that the tech do TWO separate reflashes: the engine ECU and the PHEV ECU. This tech appears to have only done the engine ECU (or perhaps the PHEV ECU reflash failed). So the car ended up with incompatible firmware in the two ECUs. By chance, things worked OK when the weather was warm, but everything went to hell in a handcart when the coolant temp was <10C. This probably also explains why there was only a generic DTC, with no indication what was wrong.

Again: Huge thanks to David Evans and his crew at Brighton Mitsubishi for fixing it. (At this stage, I'm not naming the dealer that screwed this up. And don't bother looking back in the group—I've already checked that I haven't mentioned them already!)
 
Rich, thanks so much for the clear hypothesis and write up, it was like being back at school! :)

I'm pleased you found a solution. I'm 10miles to the west of you and may have been tempted to guess the dealer to avoid them but the dealer network are too expensive for me so I intend on having it serviced locally
 
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