#relay
5 posts in Car Diagnostics blog about "relay" — OBD-II diagnostics, DTC codes, repair. ← All posts
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P0616 and P0617: starter relay circuit low and high
A click and no crank sends most people to the starter motor. These codes point at the circuit that commands it, which is usually cheaper and easier to reach.
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P0645 and P0646: A/C clutch relay control circuit
The compressor clutch is switched by a relay like any other high-current load. When the circuit faults, the air conditioning stops — and so does a lot of guesswork about refrigerant.
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P0685 to P0687: ECM power relay control circuit
The relay that keeps the engine computer alive after you switch off. When it misbehaves, the symptoms are a flat battery and codes that make no sense.
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P0230 to P0232: fuel pump primary circuit faults
These codes are about the circuit that switches the pump, not the pump itself. The distinction is worth several hundred in parts.
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P0480 and P0481: cooling fan relay control circuit
A cooling fan that does not run produces a very specific pattern: fine on the motorway, overheating in traffic. That pattern is the diagnosis.