CAT Engine 2623 Fault Code: 5 Volt Sensor DC Power Supply short to +batt

What does CAT Engine error code 2623 mean?

Code 2623 covers the 5 volt (and in the throttle position case, 8 volt) regulated sensor supply that the ECM sends out to power a whole group of analog sensors at once, things like oil pressure, intake manifold pressure, atmospheric pressure, coolant temperature, crankcase pressure, fuel pressure, and several others depending on engine family. All of these sensors share the same supply rail and a common return line back to the ECM.

When the ECM sees that supply voltage climb above its normal regulated band, it assumes the rail has shorted to a higher voltage source, most commonly battery positive. Since the ECM cannot trust any sensor reading on that rail anymore, it flags every analog sensor connected to it as invalid and substitutes default values so the engine keeps running on estimated data instead of real readings.

The ECM's internal power supply circuit is short circuit protected, so a short to battery will not damage the ECM itself. The sensors are a different story: they are not protected from overvoltage, so a supply line short to battery positive can burn out one or more sensors. If 2623 or a related 5 volt supply code is active, plan on checking every sensor on that circuit for damage, not just fixing the wiring.

What triggers a CAT Engine 2623 code?

Different ECM software versions on this code family use slightly different thresholds. Some versions trigger when the analog sensor supply is read above 5.2 volts DC for two seconds, with the ECM required to have been powered for at least three seconds first. Other versions state the analog sensor supply voltage is above normal for one second. Normal supply voltage is 5.0 ± 0.2 volts DC (with the throttle position sensor supply normally running at 8.0 ± 0.4 volts DC). A related steady-signal code on the same supply activates if a pressure sensor signal stays abnormally flat for more than 30 seconds, and a separate missing-supply code activates if the 5 volt supply disappears at the sensor entirely.

Common causes of 2623

• Damaged, corroded, or chafed connectors and wiring on the 5 volt sensor supply circuit
• Electrical problem inside one of the sensors fed by this supply
• A sensor that has failed and needs to be replaced
• An intermittent connection issue in the harness
• The supply wire shorted to another wire in the harness, to a higher voltage source, or to engine ground
• A defective or failed ECM
• An open circuit in the analog sensor common (return) wire
• A short between the 5 volt supply wire and the analog sensor common wire

How to troubleshoot CAT Engine 2623: first checks

1. 1Check for active sensor-specific fault codes first. If any are present alongside 2623, assume a sensor may already be damaged from overvoltage and inspect it before doing anything else.
2. 2Inspect the sensor supply connectors and wiring for corrosion, chafing, pinched wires, or contact with battery positive, paying attention to the ECM connector pins that carry the 5 volt supply and the analog return.
3. 3Check the harness for a short between the 5 volt supply wire and another wire, or between the supply and ground, using a multimeter with the harness disconnected from the ECM.
4. 4Verify actual supply voltage at a sensor connector with a meter and compare it against the expected 5.0 ± 0.2 volts DC (or 8.0 ± 0.4 volts DC for the throttle position sensor circuit) to confirm whether the overvoltage is present at the sensor end or only at the ECM.
5. 5If wiring and connectors check out, test or swap the suspect sensor, since an internal sensor fault can also pull the shared supply rail out of range.
6. 6If the circuit and sensors check out clean, consider that the ECM itself may be at fault, though this should be the last item ruled out.

How the code clears

No separate reset procedure is listed for this code. Once the underlying short or damaged component is repaired, the code should stop being active on its own, but you should still confirm on a scan tool that it clears and check for any newly active sensor codes that would indicate leftover sensor damage before returning the machine to service.

Affected models and serial ranges

2623 appears in our records across 10 CAT Engine models. Match your machine by model and serial number.