Experiencing Emissions test fails at highway speed near Manchester, NH?
Replacing parts blindly based on symptoms can be expensive and frustrating. Our ASE-certified technicians run live scanner data, pressure tests, and wiring inspections to find the exact root cause.
Safety Guidance: Use caution if visibility, lighting, electrical power, or occupant comfort is impaired, and obtain diagnosis if the condition persists or worsens.
Common Causes for Emissions test fails at highway speed
- Exhaust leak
- Catalytic converter restriction
- Oxygen sensor fault
- EGR system fault
- Evaporative emissions leak
Related Diagnostic Trouble Codes
These codes frequently trigger or accompany Emissions test fails at highway speed:
P0420
Catalyst System Efficiency Below Threshold Bank 1
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P0430
Catalyst System Efficiency Below Threshold Bank 2
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P0401
EGR A Flow Insufficient Detected
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P0455
EVAP System Leak Detected - Large Leak
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P0130
O2 Sensor Circuit Bank 1 Sensor 1
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