P0812: Reverse Input Circuit
Methodology: Reviewed against the SAE J2012 generic DTC definition and NHTSA complaint patterns, then kept at generic code level because this page is not scoped to one make or model.
Sources: SAE/OBD-II definitions, manufacturer service information, and public reliability reports (including NHTSA where applicable).
- SAE J2012 Diagnostic Trouble Code Definitions — Generic diagnostic trouble code definition reference for P0812.
- NHTSA recalls, complaints, and manufacturer communications — Used to check public complaint context, recall status, and safety-related manufacturer communications by VIN or vehicle.
Limits: Guidance is informational and may not match every model-year or revision. Confirm with the official manual and diagnostics before replacing parts. For safety-critical or electrical work, use a qualified technician.
What Does P0812 Mean?
P0812 code: Reverse Input Circuit. Symptoms, likely causes, diagnostic path, severity, and repair cost context.
Symptoms of P0812
- ⚠️ Warning light or diagnostic trouble code is stored
- ⚠️ Symptoms vary by vehicle and by the system that set the code
- ⚠️ Related codes, freeze-frame data, and live data are needed before replacing parts
- ⚠️ Vehicle may fail an emissions or safety inspection until the code is resolved and monitors reset
Common Causes
- 🔍 Circuit, sensor, actuator, wiring, connector, module, or mechanical condition detected by the relevant control module
- 🔍 Low battery voltage, poor ground, corrosion, water intrusion, or intermittent connector contact
- 🔍 Vehicle-specific calibration or service bulletin condition that must be checked by VIN
Real Owner Reports
From NHTSA complaint database — actual owner descriptions.
"I WENT TO A MECHANIC TODAY, I HAVE 'PASSENGER AIRBAG OFF LIGHT FLASHING' HE TOLD ME HONDAS HAVE RECALLED FOR AIRBAGS IN DEALERSHIPS SO I CHECKED MY VEHICLE REPORT IT SAYS THAT I HAD 2 RECALLS IN 2019 AND I DID THEM BUT I DIDN'T. 'RECALL SUBJECT: AIR BAGS: PASSENGER SIDE FRONTAL REPORT RECEIPT DATE:"
— Honda Civic owner, 2018-12-29
Source: NHTSA Complaints Database
Most Reported Vehicles for P0812
Based on NHTSA owner complaint data.
| # | Vehicle | Reports |
|---|---|---|
| 1 | HONDA CIVIC |
Frequently Asked Questions
Is P0812 enough to replace a part?
Can I drive with P0812?
What To Do Next
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1
Find your vehicle above
Click your make and model for real owner reports and common causes specific to your vehicle.
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2
Check for recalls
Go to nhtsa.gov/recalls and enter your VIN. Free repairs if covered.
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3
Get a professional diagnosis
A code alone doesn't identify the exact failed part. A diagnostic ($50–$150) pinpoints the root cause.