C1727: How to Diagnose & Fix — EPS Motor Circuit Malfunction
3 vehicles · 2 makes · $300-$2,500 repair
How to diagnose and fix C1727: 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.
Ford Expedition · 2003–2017
The 2003-2017 Ford Expedition with the optional air suspension suffers from air suspension compressor failure, air spring leaks, and ride height sensor malfunctions. The compressor, located under the vehicle, is exposed to road debris, salt, and moisture which degrades the motor and valves. When air springs develop leaks, the compressor runs continuously trying to maintain ride height, leading to premature burnout. Compressor replacement typically costs $666-$724, though dealer pricing can reach $1,200. Strutmasters.com notes that 2007-2011 Expedition and Navigator share the same air suspension system and failure patterns. Many owners opt for air-to-coil spring conversion kits as a permanent, lower-cost solution.
Common Symptoms
- Rear of vehicle sagging or sitting noticeably lower
- Air suspension warning light or message on dash
- Compressor runs excessively or continuously
- Loud compressor noise from under the vehicle
- Harsh ride over bumps
- Vehicle leans to one side
- Hissing sound from air springs or compressor
- Vehicle bottoming out on speed bumps or driveway transitions
How to Fix
The most cost-effective permanent fix is an air-to-coil spring conversion kit from Strutmasters or Arnott ($300-500 for kit plus installation). If keeping air suspension: replace the compressor (Arnott P-2936 or Dorman 949-200, $200-400 part), both rear air springs ($150-250 each), and inspect all air lines for cracks. Always replace air springs in pairs. Compressor relay should also be checked - a corroded relay causes intermittent compressor operation. Shop compressor replacement typically runs $666-724.
Sources for this issue (2)
Lincoln Aviator · 2020–2024
2020-2024 Aviators with the optional Air Glide suspension use an air-spring system unique to the Aviator; the related Ford Explorer was not offered with air suspension. Owners report compressor noise becoming progressively louder by 40,000-80,000 miles, then bag leaks (rear first), then compressor burnout. Warning message: "Service Air Suspension."
Common Symptoms
- rear sag overnight
- compressor runs constantly
- service air suspension message
- uneven ride height
How to Fix
Diagnose with FORScan to confirm air bag vs. compressor failure. OEM bags $700-$1,100 per corner installed. For the front, Ford SSM 51640 now supplies complete front air spring/strut assemblies (LC5Z-3C098-A/C non-hybrid, LC5Z-3C098-B/D hybrid) and recommends replacing the full assembly. Compressor (Wabco/Continental unit) ~$600-$900 installed. Replace compressor dryer at the same time as a bag (~$80) — extends compressor life. If a suspension fault message with DTCs B1041/U2100 appears after a repair, SSM 51621 says the module may be stuck in diagnostic service mode; clear it with FDRS Transport and Factory Mode Deactivation rather than replacing parts.
What you need to fix it
Only diagnosis- and fitment-reviewed repair parts are linked here.
- LC5Z-5A891-Q genuine Ford rear air spring, driver side, gas 3.0LOEMLC5Z-5A891-Q
Replace a leak-confirmed left/driver rear spring on a non-PHEV Air Glide Aviator Fitment/availability: Live Add to Cart page identifies driver side, replaces LC5Z-5A891-K and lists 2020-2025 Aviator 3.0L gas fitment. Confirm VIN, Air Gli…
- LC5Z-5A891-R genuine Ford rear air spring, passenger side, gas 3.0LOEMLC5Z-5A891-R
Replace a leak-confirmed right/passenger rear spring on a non-PHEV Air Glide Aviator Fitment/availability: Live Add to Cart page identifies passenger side, replaces LC5Z-5A891-J and lists 2020-2025 Aviator 3.0L gas fitment. Confirm VIN, …
- LC5Z-5A891-N genuine Lincoln rear air spring, driver side, 3.0L PHEVOEMLC5Z-5A891-N
Replace a leak-confirmed left/driver rear spring on an Air Glide Grand Touring PHEV Fitment/availability: Live Add to Cart page identifies driver side, replaces LC5Z-5A891-M/-E and lists 2020-2023 Aviator 3.0L PHEV fitment. Do not substi…
- LC5Z-5A891-P genuine Ford rear air spring, passenger side, 3.0L PHEVOEMLC5Z-5A891-P
Replace a leak-confirmed right/passenger rear spring on an Air Glide Grand Touring PHEV Fitment/availability: Live Add to Cart page identifies passenger side, replaces LC5Z-5A891-L/-G and lists 2020-2023 Aviator 3.0L PHEV fitment. Do not…
- LC5Z-5319-C genuine Ford air-suspension compressor/leveling assemblyOEMLC5Z-5319-C
Replace a compressor that fails electrical, command, pressure, run-time or thermal diagnosis after leaks are repaired Fitment/availability: Live official Ford direct product page identifies SKU LC5Z5319C and the four-corner air-suspensio…
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Sources for this issue (3)
Lincoln Town Car · 2003–2006
Final-gen Town Car (2003-2011 Panther platform) used a rear-only air suspension that develops bag leaks and compressor burnout. Cars sag dramatically overnight; the compressor cycles continually trying to refill.
Common Symptoms
- rear sag
- compressor runs continuously
How to Fix
Replace bags as a pair. Replace the compressor and dryer if the compressor has failed. Many owners convert to coil springs — loses self-leveling but no further maintenance. Limo owners need to keep air for headroom adjustment.
What you need to fix it
Only diagnosis- and fitment-reviewed repair parts are linked here.
- Arnott A-2105 rear air spring, two requiredOEMArnott A-2105
This issue is scoped to 2003-2011; confirm factory air equipment and order quantity two.
- AM AutoParts AM-1906992999 air-suspension compressor with dryerOEMAM-1906992999
Do not install it as a first response to rea
- Arnott C-2615 rear coil-spring conversion kit with rear shocksOEMArnott C-2615
Confirm 2003-2011 application and explain the loss of automatic load leveling before purchase; it is not the defau
As an Amazon Associate, we earn from qualifying purchases; other part links may also earn au7o a commission. Confirm fitment by VIN before buying.
Sources for this issue (3)
- air suspension of 2003 Lincoln town car (CarGurus)owner-forum
- Lincoln Town Car suspension problems (TrueDelta)owner-reports-database
- my 2006 lincoln town car looks like the rear has sunk (CarGurus)owner-forum
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C1727 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 C1727 mean?
C1727 stands for "EPS Motor Circuit Malfunction." C1727 is a steering/chassis code indicating a malfunction in the Electric Power Steering (EPS) assist motor circuit. This motor provides the actual steering boost, and the EPS module monitors its electrical circuit for proper operation. When it detects an open, short, over-current, or otherwise out-of-spec condition in the motor circuit, it sets this code. It generally causes loss or reduction of power-steering assist (heavy, hard-to-turn steering) and an EPS/steering warning light, though the vehicle can still be steered manually with more effort.
What are the most common causes of C1727?
The most common causes of C1727 are: Failed EPS assist motor, Open, shorted, or high-resistance wiring to the motor, Corroded or loose motor power/connector terminals, Low system voltage or poor ground to the EPS unit, Internal EPS control module driver fault, Overheated/over-current condition from excessive load, Damaged harness near the steering column or rack. The specific cause varies by vehicle.
How much does it cost to fix C1727?
Repair costs for C1727 range from $300 to $2,500, depending on the vehicle and root cause.
Which vehicles are affected by C1727?
Au7o has documented C1727 across 3 vehicle models from 2 manufacturers: Ford, Lincoln.
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Content compiled with AI assistance using NHTSA complaints, TSBs, and owner reports. May contain errors. Always verify with your vehicle's service manual.