MID 128 PID 100 FMI 1: Engine Oil Pressure Too Low (Volvo D11/D13/D16)

MID 128 PID 100 FMI 1 - Engine Oil Pressure Too Low

**Real-World Background**: This fault triggers when the ECM detects voltage on pin EA14 below the alarm limit (typically below 0.08V or below 2.3V depending on calibration) [citation:1][citation:7]. On Volvo D13 engines, this often appears after 500,000 miles and can be intermittent—truck loses power, then recovers [citation:4].

🚨 What Makes This Fault Tricky

The oil pressure sensor on Volvo D11/D13/D16 engines is located on the engine block between the power steering pump and the ECM [citation:7]. A very common failure mode is **oil seeping into the sensor connector**—you'll find oil inside the electrical connector when you unplug it. This creates intermittent signals and false low-pressure warnings.

🔍 Step-By-Step Diagnosis

**First, confirm the fault is real:**

1. Connect a mechanical oil pressure gauge (screw into sensor port or use test port)

2. Compare readings at idle (warm oil) vs 1500 RPM

3. Specs vary by engine, but typically: idle > 10 psi, 1500 RPM > 30-40 psi

**If mechanical pressure is GOOD:**

• Suspect sensor or wiring issue
• Unplug sensor and check for oil in connector (this is your smoking gun)
• Check for 5V reference and ground at sensor
• Monitor sensor voltage while wiggling harness

**If mechanical pressure is TRULY LOW:**

• Check oil level FIRST (surprisingly common)
• Inspect oil for fuel dilution (sniff test, or send sample)
• Check relief valve operation (located in oil filter housing)
• Consider worn bearings if mileage > 500k miles [citation:4]

🛠️ Parts & Images

**Free-to-use reference images:**

• Oil pressure sensor location: Search Commons.wikimedia.org for "Volvo D13 engine" (various angles show sensor location)
• Oil pressure test port adapter: Look for "mechanical oil pressure gauge connected" images (these are generic tools, no copyright issues)

📝 Technician Notes from the Field

*"On Volvo FH12 420, the oil pressure warning came on only above 1450 RPM. After investigation, found the sensor connector had oil in it. Cleaned connector, replaced sensor, problem gone for 2 years."* — Truck-diagnost forum user [citation:7]

*"Don't ignore the simple stuff. Had a truck towed in with this code and no oil pressure. Someone had drained oil for service and forgot to refill."* — Real shop story

⚠️ Critical Warning

If mechanical oil pressure is truly low, continued operation WILL cause catastrophic engine failure. Do not reset and ignore—verify with mechanical gauge first.