Sensor Reference Voltage A Circuit/Open
There’s a problem with the reference voltage for one of the sensors.
Heads up: this code wasn't in our hand-written library yet, so DiagCoach AI built this page on the fly. Double-check critical specs against service info before condemning parts.
What it means (plain English)
The computer sends out a 5-volt reference to sensors for readings; if it doesn't see this voltage come back, it raises an error.
What the computer is actually seeing
The Engine Control Module (ECM) expects to see between 4.5V to 5V on the sensor reference circuit. If it detects less than 4.5V or an open circuit, it triggers a fault code P0658.
What a healthy reading looks like
Reference voltage should be around 5V; a reading below 4.5V indicates a problem.
Guided diagnostic — the DiagCoach way
Don't just throw parts at it. Walk through these in order — each step tells you whether to keep going or stop and fix what you found.
- 11. Check the wiring and connectors for the sensor associated with the fault. Look for any visible damage or corrosion. - Decision: If wiring is damaged, repair it. If not, proceed to step 2.
- 22. Disconnect the sensor and measure the voltage at the connector. You should see approximately 5V. - Decision: If you see 5V, the sensor is likely faulty. If you see less than 4.5V, proceed to step 3.
- 33. Check for shorts to ground in the sensor reference wire back to the ECM. Use an ohmmeter to test continuity. - Decision: If there’s a short, repair it. If no short is found, replace the ECM.
Common causes
- Open circuit in the sensor reference wiring
- Faulty sensor drawing too much current
- Poor connection at the sensor or ECM
- Short to ground in the reference wire
Typical repair cost
$$$
Related codes
Frequently asked questions
Is it safe to drive the vehicle with this code?
It's not likely to cause immediate danger, but performance may be affected, so fix it soon.
Will this code come back after I clear it?
If the underlying issue isn't resolved, the code will likely return.
Why does this code sometimes pair with P0657?
P0657 also deals with output voltage issues, indicating a related fault either in the same circuit or sensor.
Working a real vehicle right now?
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