JCB 0x00 – ECU: Fuel Temperature ADC Fault

The Engine Control Unit (ECU) has detected a fault related to the fuel temperature analog-to-digital converter (ADC). This indicates an issue with the conversion of the fuel temperature analog voltage signal into a digital format for processing, meaning the signal is outside the expected range or not being received correctly. Because the ECU uses this data to adjust the air-fuel ratio and injection timing, an incorrect reading reduces engine efficiency and typically triggers a reduction in engine torque to prevent potential damage.

• JS115 AUTO
• JS130LC
• JS145LC
• JZ140
• JS160 T3
• JS200
• JS220
• JS220 CHINA
• JS240
• JS290

1. 1

   Visually inspect the fuel temperature sensor's wiring harness for chafing, melting, or fraying, and check connectors for corrosion or bent/loose pins

2. 2

   Scan for other active fault codes, as other system faults can sometimes trigger this code

3. 3

   Observe live data for the fuel temperature using a diagnostic tool like JCB ServiceMaster; a reading stuck at a minimum/maximum (e.g., -40°C) or unchanging indicates a circuit or sensor problem

4. 4

   Consider ambient temperature, as extreme cold (below -20°F or -30°F) can trigger a fuel temperature sensor performance code

1. 1

   Disconnect power

   Turn off the machine and disconnect the battery before working on electrical components.

2. 2

   Check wiring harness continuity and shorts

   Disconnect the 2-pin sensor connector. Check for continuity on the signal and ground wires to the ECU (a lack of a beep or an 'OL' reading indicates a break in the wire). Check for a short to ground (no continuity should exist to chassis ground) and short to power (no voltage should be present on the signal wire with ignition on).

3. 3

   Test the sensor resistance

   Measure resistance across the sensor pins and compare the measured resistance to the specifications in the JCB service manual for your specific machine and engine. Resistance should decrease as temperature increases (e.g., ~24.7 kOhms at 86°F/30°C). If the reading is infinite (open circuit) or zero (short circuit), replace the sensor.

4. 4

   Check voltage supply

   Reconnect the battery and turn the ignition on (engine off). Measure voltage at the harness connector. It should show a 5V reference from the ECU and a ground. If missing, the issue may be the ECU or wiring.

5. 5

   Replace components and clear codes

   Replace the faulty sensor or repair damaged wiring. Clear the fault codes using a diagnostic tool and run the machine to verify the fix. If all wiring and the sensor test correctly, the fault may lie within the Engine Control Unit (ECU), which is a rare occurrence requiring further specialized testing or replacement by a qualified technician.