P1026 on 2019-2020 Lincoln Nautilus (Standard, Select, Reserve) — Engine Coolant Temperature Sensor 1 / Cylinder Head Temperature Sensor 2 Correlation
1 vehicles · 1 makes · $600-$9,000 repair
How to diagnose and fix P1026: 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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P1026 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 P1026 mean?
P1026 stands for "Engine Coolant Temperature Sensor 1 / Cylinder Head Temperature Sensor 2 Correlation." The PCM cross-checks the engine coolant temperature (ECT) sensor against the cylinder head temperature (CHT) sensor. P1026 sets when the two readings disagree by more than a calibrated amount, meaning one sensor is reading incorrectly or coolant is not actually present at the ECT sensor while the head is heating. Ford TSB 20-2234 lists P1026 among the codes (with P0128, P0217, P044C, P1285, P1299, P139A, P2457) stored on 2019-2020 Edge / Lincoln Nautilus 2.0L EcoBoost vehicles suffering coolant loss from a cracked EGR cooler; because the PCM uses this correlation to protect the engine, it will often move into a fail-safe cooling / reduced-power strategy.
What are the most common causes of P1026?
The most common causes of P1026 are: Coolant loss — notably a cracked or leaking EGR cooler on 2.0L EcoBoost (Ford TSB 20-2234), Low coolant level or air trapped in the cooling system so the ECT sensor is not immersed, Failed or drifting ECT or CHT sensor, Damaged ECT / knock-sensor wiring harness (a known 2.7L EcoBoost concern), Outdated PCM calibration (TSB update required), Stuck thermostat or other cooling-system fault causing genuine temperature divergence. The specific cause varies by vehicle.
How much does it cost to fix P1026?
Repair costs for P1026 range from $600 to $9,000, depending on the vehicle and root cause.
Which vehicles are affected by P1026?
Au7o has documented P1026 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.