C1727: How to Diagnose & Fix — EPS Motor Circuit Malfunction
4 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 optional air suspension (standard on Eddie Bauer, King Ranch, Platinum, and EL/MAX trims) 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. RepairPal estimates compressor replacement between $666 and $724, though dealer pricing can reach $1,200. NHTSA has received hundreds of complaints regarding air suspension failures. 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
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. RepairPal estimates $666-724 for compressor replacement at a shop.
Sources for this issue (2)
Lincoln Town Car · 2003–2011
Final-gen Town Car (2003-2011 Panther platform) used a rear-only air suspension that develops bag leaks and compressor burnout very similar to the Navigator/Crown Vic Police Interceptor system. Cars sag dramatically overnight; compressor cycles continually trying to refill.
Common Symptoms
- rear sag
- compressor runs continuously
- air suspension warning
- rear bottoms out on bumps
How to Fix
Replace bags as a pair ($300-$600 aftermarket installed). Compressor + dryer kit ~$200-$400 installed. Many owners convert to coil springs with a Strutmasters-style kit (~$300-$500) — 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
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Lincoln Navigator · 2003–2017
Lincoln Aviator · 2020–2024
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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 4 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.