P0643 on Nissan Xterra
Sensor Reference Voltage A Circuit High
Methodology: Reviewed against the SAE J2012 generic DTC definition and NHTSA owner-complaint patterns, then scoped to Nissan Xterra context without treating complaints as confirmed diagnoses.
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 P0643.
- NHTSA recalls, complaints, and manufacturer communications — Used to check public owner 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 P0643 Means on Your Nissan Xterra
P0643 is a diagnostic trouble code indicating: Sensor Reference Voltage A Circuit High. This code relates to the computer and output circuits system. The vehicle's computer detected a condition outside normal operating parameters and stored this code.
Real Nissan Xterra Owner Reports
Source: NHTSA Complaints Database
"Error code on 2005 nissan xterra - p0643 has shown up on many models with this engine. noted on an emission inspection for annual tx inspection."
"Nissan xterra 2006, both front cats have failed. dealer said due to ethanol a common problem, cost around $2300. found cats and a mechanic for $1200. after 3 weeks check engine light returned. i am now getting a p0643."
All reports filed by vehicle owners directly with the U.S. Department of Transportation.
📊 Complaint Trend by Model Year
Common Causes on Nissan Xterra
Based on NHTSA complaint component analysis for this vehicle.
What To Do Next
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1
Check for recalls on YOUR VIN
Go to nhtsa.gov/recalls and enter your VIN. If your vehicle is covered, repairs are free.
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2
Get a proper diagnosis
A code alone doesn't tell you the exact failed part. A diagnostic at a shop ($50–$150) pinpoints the root cause before you spend money on parts.
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3
Compare repair quotes
Get 2–3 quotes. Dealer vs. independent shop prices often differ 30–50% for the same repair.