P1660 on 1994-1999 Acura Integra (LS, GS, RS, Special Edition) — Output Circuit Check Signal High
1 vehicles · 1 makes · $150-$3,500 repair
How to diagnose and fix P1660: 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.
Acura Integra · 1994–1999
The Honda MP7A/SP7A/S4XA 4-speed automatic in the Integra is notoriously sensitive to fluid condition and shift-solenoid contamination. Solenoid A/B failure causes flashing D4 light, harsh or missed 2-3/3-4 shifts, loss of power in D4/D3, and sometimes speedometer drop-out. Shifting problems can also stem from a clogged transmission filter or screen restricting fluid flow, which lowers hydraulic pressure and leads to missed 4th-gear shifts and failure to downshift. In one owner report, the car suddenly lost almost all power in D4, would not shift, and the speedometer stopped working; the codes returned were Automatic Transaxle FI A circuit failure and ELD error.
Common Symptoms
- flashing D4 indicator
- harsh 2-3 shift
- no 4th gear
- loss of power in D4/D3
- speedometer intermittent
- shift hold in gear
How to Fix
Drain-and-fill with Honda ATF-Z1/DW-1 (never use generic Dexron — it will destroy the clutches). Change the fluid every 3 years/36,000 miles; it breaks down with heat and wear just like engine oil. Pull codes with a Honda jumper or scan tool; the lock-up and shift solenoids are external, three-bolt parts accessible from the engine bay and often just need cleaning. A failed lock-up solenoid sets a general Code 70 (Automatic Transaxle) check-engine light; the solenoid costs less than $200 to replace.
What you need to fix it
Only diagnosis- and fitment-reviewed repair parts are linked here.
- Genuine Honda 08200-9008 ATF DW-1 (ATF-Z1), 2 quarts
Repair fluid Honda/Acura automatics requiring ATF-Z1 or DW-1; the issue is specifically the Integra four-speed automatic.
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Owner tips & cautions
- WarningUse only Honda ATF-Z1 or DW-1. Generic ATF causes shift flare and premature failure.
- TipPull the specific solenoid code before condemning the transmission — a $150 solenoid often fixes it.
Sources for this issue (2)
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P1660 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 P1660 mean?
P1660 stands for "Output Circuit Check Signal High." This is a manufacturer-specific code (seen on Ford and some GM applications) indicating the computer detected an abnormally high voltage on an output circuit monitoring line, suggesting a controlled output (such as a solenoid or relay driver) is not switching as expected. It generally reflects an electrical/circuit problem between the PCM and the device it controls rather than a mechanical failure. Symptoms vary widely depending on which output is affected. Because exact behavior is manufacturer-specific, confirming the definition for the specific vehicle is recommended.
What are the most common causes of P1660?
The most common causes of P1660 are: Wiring short to voltage in an output circuit, Faulty output driver or relay, Corroded or loose connector on the affected circuit, Open ground in the output circuit, Faulty controlled component (solenoid/relay), PCM internal driver fault (less common). The specific cause varies by vehicle.
How much does it cost to fix P1660?
Repair costs for P1660 range from $150 to $3,500, depending on the vehicle and root cause.
Which vehicles are affected by P1660?
Au7o has documented P1660 across 1 vehicle models from 1 manufacturers: Acura.
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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.