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Level: Critical

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 (Volvo D11/D13/D16). Symptoms (5), causes (6), and fixes (6). What to check first to prevent derate and downtime. Critical: don’t ignore.

CodeMID 128 PID 100 FMI 1
SeverityCritical
Applies toVaries by OEM configuration (confirm your exact calibration)
Can I drive?Not recommended. MID 128 PID 100 FMI 1 is marked critical and may escalate into derate or shutdown. Diagnose immediately and confirm whether the fault is ACTIVE vs stored (steps below).
Symptoms
5
Likely causes
6
Fixes
6
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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 that affects performance, protection strategy, or emissions (depending on calibration).

OEM definitions can vary slightly, so confirm your exact meaning with your service manual or diagnostic tool.

Treat repeat faults as ACTIVE and diagnose using a scan tool 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 vs actual sensor readings, timing windows, and plausibility checks.

A single event might store a code, but repeated events across drive cycles are what typically trigger warnings, derate strategies, or inducement (emissions systems).

Your goal is to identify the failure mode (electrical, mechanical, sensor drift, or upstream cause) rather than “parts cannon” replacement.

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. If it’s not active, look at last occurrence conditions (freeze-frame if available).
  • Record companion codes. Fixing the “first” code often makes others disappear.
  • Clear and re-test under similar conditions. If it returns quickly, you have a repeatable fault (good for diagnosis).

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. Run actuator tests (if supported). Use OEM diagnostic software (examples: Cummins INSITE, Detroit DDDL, PACCAR DAVIE4) (or a capable J1939 tool) to command tests when available.
  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 → check connector/harness first → then confirm sensor values and plausibility → then consider component testing.
  • If you have multiple codes → diagnose the earliest/most upstream code first.

Common misdiagnosis mistakes for MID 128 PID 100 FMI 1

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  • Replacing sensors without checking wiring, grounds, and connector pin fitment.
  • Clearing codes repeatedly without confirming whether the fault is ACTIVE and repeatable.
  • Missing companion codes that point to the real upstream problem.

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

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Critical aftertreatment faults can trigger rapid derate depending on calibration. Some trucks reduce torque quickly and may progress to severe speed limiting if the fault stays active.

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/derate 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 actuator tests and live data

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. Many faults escalate into derate when ignored.

Related fault codes

No related faults found yet. Commonly seen with: SPN 5246, SPN 1569, SPN 4364, SPN 3719.

Mechanic community notes for MID 128 PID 100 FMI 1

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Real-world tips from technicians. Submissions are moderated to keep spam and “my cousin fixed it with duct tape” content out.

No community notes yet. Be the first to add a practical fix that actually works in real life.

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Keep it useful: symptoms, what you checked, what fixed it, and whether the code stayed inactive after a drive cycle.

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