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MID 128 PID 100 FMI 1Severity: Critical

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

Quick Answer

When MID 128 PID 100 FMI 1 sets, the ECM is indicating a fault condition involving the component or system named in the code.

OEM definitions and thresholds can vary, so confirm the exact meaning with service information or a capable diagnostic tool.

Code
MID 128 PID 100 FMI 1
Severity
Critical
Applies to
Check OEM application
Can I drive?
Avoid unnecessary driving until MID 128 PID 100 FMI 1 is diagnosed. A critical fault can affect engine protection, emissions operation, or drivability depending on the OEM calibration and companion codes. Confirm whether the fault is ACTIVE and check for stop-engine, derate, or inducement warnings.

Common Symptoms

  • Oil pressure gauge reads 0 or abnormally low
  • Red warning lamp on dash illuminates
  • Engine power reduction (derate)
  • Engine may shut down below 5 mph

Likely Causes

  • Faulty oil pressure relief valve stuck open
  • Low oil level or incorrect viscosity
  • Contaminated oil (fuel dilution, sludge)
  • Worn oil pump or worn engine bearings

Quick Diagnostic Checks

Check first
  1. 1Scan for companion codes and record freeze-frame data (if available).
  2. 2Inspect connectors, harness rub points, and pins for corrosion.
  3. 3Check for other active faults that may be upstream causes (communications, sensors, air/fuel issues).
  4. 4After repair, clear codes and confirm the fault stays inactive after a drive cycle.

Common Fixes

  • Verify actual oil pressure with mechanical gauge
  • Check oil level and condition (fuel smell? milky?)
  • Inspect sensor connector for oil intrusion
  • Replace oil pressure sensor if connector has oil
Full Technical Guide ↓Share This Fault
Full technical sections↓
FitmentsMeaningHow it worksImagesDetailed guideOEM/Engine notesLocation hintScan tool checksStep-by-step diagnosticDecision guideMisdiagnosisDerate/inducementChecklistToolsPreventionCommunity discussionsCommunity videosCommunity notesShare

What does MID 128 PID 100 FMI 1 mean?

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When MID 128 PID 100 FMI 1 sets, the ECM is indicating a fault condition involving the component or system named in the code.

OEM definitions and thresholds can vary, so confirm the exact meaning with service information or a capable diagnostic tool.

Treat repeat faults as ACTIVE and diagnose using live data, wiring checks, and basic inspections before replacing parts.

How this system works (why MID 128 PID 100 FMI 1 happens)

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Most modern fault logic is based on expected versus actual sensor readings, timing windows, circuit checks, and plausibility tests.

A stored code can come from a temporary event, while a repeatable active code gives you a much better diagnostic target.

The goal is to identify whether the failure is electrical, mechanical, sensor-related, or caused by another upstream fault before replacing components.

Detailed guide for MID 128 PID 100 FMI 1

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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.

Location hint for MID 128 PID 100 FMI 1

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Component location varies by OEM and chassis. Use your engine’s service manual to confirm the sensor/valve location before replacing parts.

Tip: Inspect connectors and harness routing before replacing parts.

Scan tool checks for MID 128 PID 100 FMI 1

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  • Check status: ACTIVE vs INACTIVE / stored and review freeze-frame data when available.
  • Record companion codes and diagnose the earliest or most upstream fault first.
  • Compare live sensor values with expected operating conditions and inspect wiring and connectors.
  • Clear and re-test under similar conditions only after completing the initial inspection.

If your tool can’t run actuator tests, you can still diagnose a lot with careful inspection + repeatability testing.

Step-by-step diagnostic for MID 128 PID 100 FMI 1

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  1. Visual inspection (fast wins). Harness routing, connector pins, hoses/lines (if applicable), and obvious damage.
  2. Check fluid sanity. Not applicable unless your fault is fluid-related. Focus on inspections + repeatability.
  3. Confirm the fault is ACTIVE. Stored-only faults can be old events.
  4. Review live data and circuit values. Use OEM diagnostic software (examples: Cummins INSITE, Detroit DDDL, PACCAR DAVIE4) or a capable heavy-duty scan tool to review the affected signal, commanded/actual values when applicable, and related sensor data.
  5. Verify after repair. Clear codes, road test, confirm it stays inactive.

Decision guide (fast path) for MID 128 PID 100 FMI 1

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  • If the fault is STORED only → inspect, clear, and monitor. If it returns, treat it as active.
  • If ACTIVE → inspect the named component, connector, harness, supply/ground, and live-data plausibility.
  • If multiple codes are present → diagnose the earliest or most upstream code first.

Common misdiagnosis mistakes for MID 128 PID 100 FMI 1

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  • Replacing sensors or components without checking wiring, grounds, connector fitment, and companion codes.
  • Clearing the fault repeatedly without confirming whether it is ACTIVE and repeatable.
  • Missing an upstream fault that is causing the displayed code as a secondary symptom.

Will MID 128 PID 100 FMI 1 cause derate or inducement?

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Critical faults can affect engine protection or vehicle operation. Follow the OEM diagnostic procedure and address active companion faults promptly.

Exact behavior depends on ECM calibration and which companion faults are active.

“Do this first” checklist for MID 128 PID 100 FMI 1

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  • Scan for companion codes and record freeze-frame data (if available).
  • Inspect connectors, harness rub points, and pins for corrosion.
  • Check for other active faults that may be upstream causes (communications, sensors, air/fuel issues).
  • After repair, clear codes and confirm the fault stays inactive after a drive cycle.

Tools needed to diagnose MID 128 PID 100 FMI 1

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  • Basic hand tools + good lighting for inspection
  • Multimeter for connector/power/ground checks (if wiring suspected)
  • OEM diagnostic software (examples: Cummins INSITE, Detroit DDDL, PACCAR DAVIE4) (or equivalent scan tool) for live data and supported diagnostic tests

Prevention tips to avoid repeat MID 128 PID 100 FMI 1

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  • Fix small wiring/connector issues early before they become repeat faults.
  • During service, inspect harness routing and clamp points near heat/vibration.
  • Don’t ignore intermittent faults. “Erratic” usually gets worse.

What to check first for MID 128 PID 100 FMI 1

  1. Inspect connectors and harness near the affected component for corrosion, rubbing, or loose pins.
  2. Check for upstream causes (communications, sensors, air/fuel issues).
  3. Check for other active faults that may be upstream causes (communications, sensors, air/fuel issues).

If the fault repeats after clearing, diagnose it as ACTIVE and review companion codes and live data before replacing parts.

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