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2012 Hino 268 inlet dpf temp fault

Techmaster

New Recruit
Mechanic
Hi guys, got an issue with 2012 Hino 268. Active code for inlet dpf temp sensor mulfuntion. Replaced sensor and code still active, live data on sensor is -20. Checked voltage at sensor and getting 4.27v I'm pretty sure it has to be 4.5 - 5. I probed the back of the supply wire at the ECM and the voltage was 4.27. Bad ECM? Or am I missing something?

Thankyou for all the help
 

Hino123

Active Expediter
Researching
Standard voltage at the sensor is 4.5-5.5 v. I would rule out all connections and load test the wires from the ECU connector to the Inlet DPR temp sensor with a headlamp to verify they will hold a load. The Exhaust gas temperature sensor 1 shares a ground with the Exhaust gas temperature sensor 3, and the DPR diff pressure sensor. An issue with one of those sensors could pull down your 5v reference voltage to 4.27.I would disconnect both and measure again. That circuit goes through 2 connectors. Moisture in either of those or some corrosion could cause the issue you are having. When you back-probed the ECU what were you using the for a ground signal? The actual sensor ground or a known good ground?You failed to mention the actual code you are getting. If I had that information I may be able to help further. Sensor terminology in those years is somewhat conflicting due to the added sensors from the burner. In my experience it is ALMOST NEVER the ECU. I have had a few, but I would want to 100% explore all avenues before. Hope this helps
 
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Techmaster

New Recruit
Mechanic
Hey, looks like temp sensor 1 was dragging the ground out. Thank-you so much for taking the time to help. Awesome work!
 
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