Mechanical Diagnostics API - Steer Autos Documentation

POST /v1/inspections/mechanical

Perform comprehensive mechanical diagnostics using OBD-II data, sensor readings, and AI-powered analysis. Detect engine issues, transmission problems, brake wear, and more.

Request

curl -X POST "https://api.steerai.autos/v1/inspections/mechanical" \
  -H "Authorization: Bearer YOUR_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{
    "vehicle_id": "veh_1234567890abcdef",
    "obd_data": {
      "dtcs": ["P0420", "P0171"],
      "live_data": {
        "engine_rpm": 850,
        "coolant_temp": 92,
        "intake_temp": 25,
        "maf_rate": 3.2,
        "throttle_position": 0,
        "fuel_pressure": 380,
        "o2_sensor_voltage": 0.45,
        "timing_advance": 15
      },
      "freeze_frame": {
        "P0420": {
          "engine_rpm": 2800,
          "vehicle_speed": 65,
          "coolant_temp": 95
        }
      }
    },
    "test_results": {
      "battery_voltage": 12.6,
      "alternator_output": 14.2,
      "brake_fluid_level": "ok",
      "engine_oil_level": "ok",
      "coolant_level": "ok",
      "transmission_fluid": "ok"
    },
    "options": {
      "include_recommendations": true,
      "severity_threshold": "minor"
    }
  }'

Request Body

Field	Type	Required	Description
`vehicle_id`	string	Yes	Vehicle identifier
`obd_data`	object	Yes	OBD-II diagnostic data
`obd_data.dtcs`	array	No	Diagnostic trouble codes
`obd_data.live_data`	object	Yes	Real-time sensor readings
`test_results`	object	No	Manual inspection results
`options.include_recommendations`	boolean	No	Include repair recommendations (default: true)
`options.severity_threshold`	string	No	Minimum severity to report: `minor`, `moderate`, `severe` (default: `minor`)

Live Data Parameters

Parameter	Unit	Description
`engine_rpm`	RPM	Engine revolutions per minute
`coolant_temp`	°C	Engine coolant temperature
`intake_temp`	°C	Intake air temperature
`maf_rate`	g/s	Mass air flow rate
`throttle_position`	%	Throttle position (0-100)
`fuel_pressure`	kPa	Fuel rail pressure
`o2_sensor_voltage`	V	Oxygen sensor voltage
`timing_advance`	°	Ignition timing advance
`vehicle_speed`	km/h	Vehicle speed
`engine_load`	%	Calculated engine load

Response

{
  "status": "success",
  "data": {
    "diagnostic_id": "mech_1234567890abcdef",
    "vehicle_id": "veh_1234567890abcdef",
    "status": "completed",
    "created_at": "2024-01-15T11:00:00Z",
    "completed_at": "2024-01-15T11:00:15Z",
    "results": {
      "overall_health": "fair",
      "health_score": 6.8,
      "confidence": 0.91,
      "systems": [
        {
          "system": "engine",
          "status": "needs_attention",
          "health_score": 7.0,
          "issues": [
            {
              "issue_id": "eng_cat_efficiency",
              "component": "catalytic_converter",
              "severity": "moderate",
              "status": "active",
              "description": "Catalytic converter efficiency below threshold",
              "dtc": "P0420",
              "confidence": 0.94,
              "symptoms": [
                "Reduced fuel efficiency",
                "Failed emissions test possible",
                "Check engine light on"
              ],
              "recommended_action": "Replace catalytic converter",
              "urgency": "medium",
              "estimated_repair": {
                "min": 800,
                "max": 1500,
                "currency": "USD",
                "labor_hours": 2.5
              }
            },
            {
              "issue_id": "eng_fuel_trim",
              "component": "fuel_system",
              "severity": "minor",
              "status": "active",
              "description": "System running lean (Bank 1)",
              "dtc": "P0171",
              "confidence": 0.88,
              "symptoms": [
                "Rough idle",
                "Slight hesitation on acceleration",
                "Decreased fuel efficiency"
              ],
              "possible_causes": [
                "Vacuum leak",
                "Dirty MAF sensor",
                "Fuel filter restriction",
                "Weak fuel pump"
              ],
              "recommended_action": "Inspect for vacuum leaks, clean MAF sensor",
              "urgency": "low",
              "estimated_repair": {
                "min": 150,
                "max": 400,
                "currency": "USD",
                "labor_hours": 1.5
              }
            }
          ]
        },
        {
          "system": "transmission",
          "status": "good",
          "health_score": 8.5,
          "issues": []
        },
        {
          "system": "brakes",
          "status": "good",
          "health_score": 8.2,
          "issues": []
        },
        {
          "system": "electrical",
          "status": "good",
          "health_score": 9.0,
          "issues": [],
          "notes": "Battery voltage and alternator output within normal range"
        },
        {
          "system": "cooling",
          "status": "good",
          "health_score": 8.8,
          "issues": []
        },
        {
          "system": "emissions",
          "status": "needs_attention",
          "health_score": 6.5,
          "issues": [
            {
              "issue_id": "emis_cat_001",
              "component": "catalytic_converter",
              "severity": "moderate",
              "status": "active",
              "description": "Emissions system efficiency degraded",
              "recommended_action": "Replace catalytic converter to meet emissions standards"
            }
          ]
        }
      ],
      "maintenance_schedule": {
        "overdue": [],
        "due_soon": [
          {
            "service": "engine_oil_change",
            "miles_remaining": 1200,
            "recommended_date": "2024-02-15"
          }
        ],
        "upcoming": [
          {
            "service": "tire_rotation",
            "miles_remaining": 3500,
            "recommended_date": "2024-04-01"
          }
        ]
      },
      "summary": {
        "total_issues": 2,
        "by_severity": {
          "minor": 1,
          "moderate": 1,
          "severe": 0,
          "critical": 0
        },
        "by_urgency": {
          "immediate": 0,
          "high": 0,
          "medium": 1,
          "low": 1
        },
        "total_estimated_repair": {
          "min": 950,
          "max": 1900,
          "currency": "USD"
        },
        "systems_affected": ["engine", "emissions"]
      }
    },
    "reports": {
      "pdf_url": "https://reports.steerai.autos/mech_1234567890abcdef.pdf",
      "json_url": "https://api.steerai.autos/v1/inspections/mechanical/mech_1234567890abcdef/report"
    }
  },
  "meta": {
    "request_id": "req_mech_xyz789",
    "processing_time": 15.123,
    "diagnostic_protocols": ["OBD-II", "CAN", "AI_Analysis"]
  }
}

Response Fields

Field	Type	Description
`diagnostic_id`	string	Unique diagnostic inspection identifier
`results.overall_health`	string	`excellent`, `good`, `fair`, `poor`, `critical`
`results.health_score`	float	Overall health score (0-10)
`systems[].system`	string	Vehicle system name
`systems[].status`	string	`good`, `needs_attention`, `critical`
`issues[].severity`	string	`minor`, `moderate`, `severe`, `critical`
`issues[].urgency`	string	`immediate`, `high`, `medium`, `low`
`issues[].dtc`	string	OBD-II diagnostic trouble code

Vehicle Systems

Engine System

Components Analyzed: • Engine performance and efficiency • Fuel system and injectors • Air intake and MAF sensor • Ignition system and timing • Oil pressure and condition • Compression and cylinder health

Transmission System

Components Analyzed: • Shifting performance • Transmission fluid condition • Clutch wear (manual) • Torque converter (automatic) • Gear ratios and synchronizers • Electronic controls

Brake System

Components Analyzed: • Brake pad/shoe thickness • Rotor/drum condition • Brake fluid level and quality • ABS functionality • Brake pressure and response • Electronic stability control

Electrical System

Components Analyzed: • Battery voltage and health • Alternator output • Starter motor function • Lighting systems • Electronic control modules • Sensor diagnostics

Cooling System

Components Analyzed: • Coolant level and condition • Radiator and hoses • Water pump operation • Thermostat function • Cooling fan operation • Temperature regulation

Emissions System

Components Analyzed: • Catalytic converter efficiency • Oxygen sensors • EVAP system integrity • EGR valve function • PCV system • Emissions compliance

Common DTCs (Diagnostic Trouble Codes)

Code	System	Description	Typical Cause
P0420	Emissions	Catalyst efficiency below threshold	Failed catalytic converter
P0171	Engine	System too lean (Bank 1)	Vacuum leak, dirty MAF
P0300	Engine	Random/multiple cylinder misfire	Spark plugs, coils, fuel
P0401	Emissions	EGR flow insufficient	Clogged EGR valve
P0456	Emissions	EVAP small leak detected	Loose gas cap, leak
P0442	Emissions	EVAP medium leak detected	Cracked hoses, purge valve

Error Responses

400 Bad Request

{
  "status": "error",
  "error": {
    "code": "INVALID_OBD_DATA",
    "message": "OBD data format is invalid or incomplete",
    "type": "validation_error",
    "field": "obd_data.live_data"
  }
}

422 Unprocessable Entity

{
  "status": "error",
  "error": {
    "code": "VEHICLE_NOT_OBD_COMPATIBLE",
    "message": "Vehicle does not support OBD-II diagnostics (pre-1996 model)",
    "type": "validation_error",
    "details": {
      "vehicle_year": 1994,
      "minimum_year": 1996
    }
  }
}

Integration with Hardware

OBD-II Adapters

Compatible Devices• Bluetooth OBD-II adapters • WiFi OBD-II adapters • USB OBD-II readers • Professional scan tools • Mobile diagnostic apps

Data Protocols

Supported Protocols• ISO 15765-4 (CAN) • ISO 14230-4 (KWP2000) • ISO 9141-2 • SAE J1850 PWM • SAE J1850 VPW

DeepDiag Integration

For advanced diagnostics beyond OBD-II, integrate with DeepDiag, our comprehensive diagnostic platform:

curl -X POST "https://api.steerai.autos/v1/inspections/deepdiag" \
  -H "Authorization: Bearer YOUR_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{
    "vehicle_id": "veh_1234567890abcdef",
    "diagnostic_level": "comprehensive",
    "include_mechanical": true
  }'

Pro Tip: Combine mechanical diagnostics with visual inspection for a complete vehicle assessment. Bundle both API calls for discounted pricing.

Webhooks

{
  "event": "mechanical_diagnostic.completed",
  "timestamp": "2024-01-15T11:00:15Z",
  "data": {
    "diagnostic_id": "mech_1234567890abcdef",
    "vehicle_id": "veh_1234567890abcdef",
    "overall_health": "fair",
    "health_score": 6.8,
    "issues_found": 2,
    "critical_issues": 0,
    "report_url": "https://reports.steerai.autos/mech_1234567890abcdef.pdf"
  }
}

Best Practices

Data Privacy: OBD-II data may contain sensitive vehicle information. Ensure you have proper authorization before collecting and transmitting diagnostic data.

Regular Diagnostics: Run diagnostics every 3,000-5,000 miles for optimal monitoring
Multiple Data Points: Collect data under various conditions (idle, acceleration, highway)
Baseline Establishment: Create baseline readings for healthy vehicles
Trend Analysis: Monitor changes over time to predict failures
Combine with Visual: Use both mechanical and visual inspections for complete assessment

API Documentation

​POST /v1/inspections/mechanical

​Request

​Request Body

​Live Data Parameters

​Response

​Response Fields

​Vehicle Systems

​Common DTCs (Diagnostic Trouble Codes)

​Error Responses

​400 Bad Request

​422 Unprocessable Entity

​Integration with Hardware

OBD-II Adapters

Data Protocols

​DeepDiag Integration

​Webhooks

​Best Practices

POST /v1/inspections/mechanical

Request

Request Body

Live Data Parameters

Response

Response Fields

Vehicle Systems

Common DTCs (Diagnostic Trouble Codes)

Error Responses

400 Bad Request

422 Unprocessable Entity

Integration with Hardware

DeepDiag Integration

Webhooks

Best Practices