P044C on 2019-2020 Lincoln Nautilus (Standard, Select, Reserve) — Exhaust Gas Recirculation Sensor "C" Circuit Low
1 vehicles · 1 makes · $600-$9,000 repair
How to diagnose and fix P044C: most-reported vehicles
Ranked by owner reports. Each card gives the symptoms, how to confirm the cause, the fix, parts and sources for that vehicle.
Lincoln Nautilus · 2019–2020
2019-2020 Nautilus models with the base 2.0L EcoBoost (non-hybrid) suffer unexplained coolant loss, white tailpipe smoke, an overheat warning, and sometimes coolant intrusion into the cylinders. Ford TSB 20-2234 traces the most common cause to a failing exhaust gas recirculation (EGR) cooler that leaks coolant internally; the related design also has a known coolant-intrusion weakness (narrow coolant slit between cylinders compromising the head-gasket seal). Owners report repeated coolant top-offs with no visible external leak, then misfires as coolant fouls the plugs. A June 2025 Ford EcoBoost coolant-intrusion class action covers 1.5L-2.0L engines; the most severe Nautilus cases require engine replacement with the redesigned block.
Common Symptoms
- Repeated low-coolant warnings / disappearing coolant with no visible leak
- White smoke from the tailpipe (especially on cold start)
- Engine overheating / over-temperature warning in cluster
- Sweet coolant smell inside or outside the vehicle
- Rough idle and misfires (coolant-fouled plugs)
- Check engine light
How to Fix
Per TSB 20-2234, perform a cooling-system pressure test and inspect the EGR cooler; replace the EGR cooler and update PCM software for the typical case. If a coolant smell, white smoke, and cylinder misfires persist (coolant intrusion past the head gasket), the durable fix is a long-block / engine replacement with the updated cross-drilled block — a head-gasket-only repair on the old-style block will fail again. Replace fouled spark plugs and flush the cooling system.
What you need to fix it
Only diagnosis- and fitment-reviewed repair parts are linked here.
- Genuine Ford K2GZ-9F464-B EGR coolerOEMK2GZ-9F464-B
Replace a cooling-system-pressure-test-confirmed internally leaking EGR cooler under the matching TSB branch Fitment/availability: Live Ships in 1-3 Business Days/Add to Cart page identifies K2GZ-9F464-B, replacement of K2GZ-9F464-A and …
- Genuine Lincoln CYFS-12Y-PCTX / Motorcraft SP-550X spark plugOEMCYFS-12Y-PCTX / SP-550X
Confirm VIN
- Motorcraft Yellow prediluted antifreeze/coolant VC-13DL-G, 1 gallonOEMVC-13DL-G
Refill and bleed the repaired system with Ford-approved service coolant after the leak is corrected Fitment/availability: Live In Stock/Add to Cart direct page identifies Motorcraft VC-13DL-G one-gallon yellow prediluted coolant. Ford ap…
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Sources for this issue (3)
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P044C code reference
General diagnostic-code context. The code alone does not confirm a cause for your vehicle; use the applicable issue card and its sources.
Frequently asked questions
What does P044C mean?
P044C stands for "Exhaust Gas Recirculation Sensor "C" Circuit Low." A generic (SAE-defined) powertrain code that applies to 1996-and-newer vehicles of any make. The engine control module has detected a lower-than-expected voltage on the circuit for EGR sensor "C" — depending on the platform this is an EGR valve position or EGR temperature sensor. The EGR system recirculates a metered amount of exhaust back into the intake to lower combustion temperature and NOx, so a faulty feedback signal means the module cannot verify EGR flow. Expect a check engine light, possible rough idle, hesitation, or reduced fuel economy, and the vehicle will fail an OBD-II emissions test while the light is on.
What are the most common causes of P044C?
The most common causes of P044C are: Failed EGR position or EGR temperature sensor providing incorrect feedback, Short to ground or open in the sensor signal or reference wiring, Corroded, damaged, or loose connector at the EGR sensor, Carbon buildup in the EGR valve, passages, or cooler causing the valve to stick, Faulty EGR valve assembly with an integrated sensor, Exhaust or intake leak near the EGR circuit skewing readings, Failed ECM/PCM (rare — verify sensor and wiring first). The specific cause varies by vehicle.
How much does it cost to fix P044C?
Repair costs for P044C range from $600 to $9,000, depending on the vehicle and root cause.
Which vehicles are affected by P044C?
Au7o has documented P044C across 1 vehicle models from 1 manufacturers: Lincoln.
Content compiled with AI assistance using NHTSA complaints, TSBs, and owner reports. May contain errors. Always verify with your vehicle's service manual.