2019 Volvo VNL 760 D13 - Erratic Idle and Stalling - SPN 651 FMI 5

Question

Driving me nuts. This 2019 Volvo starts fine, but after it warms up, the idle gets really choppy, almost like it's dropping a cylinder. I'm getting SPN 651 FMI 5 which points to Injector 1 current below normal or open circuit.

I swapped the injector with number 2 to see if the code followed the injector, but it stayed on cylinder 1. I'm thinking it's the harness under the valve cover, but it looks visually okay without any obvious chaffing.

FordGuyFrank · Accepted Answer

✅ Confirmed fix: Found a pin in the pass-through connector at the valve cover was pushed back slightly and not making solid contact. The thermal expansion of the engine was enough to lose connection when hot. Re-pinned the connector and the misfire is gone.

OTR_Carlos · Answer

It's common for the internal injector harness pigtails to fail on the D13. The heat cycles make the plastic brittle and the wires vibrate until they micro-break inside the insulation.

2019 Volvo VNL 760 D13 - Erratic Idle and Stalling - SPN 651 FMI 5

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