Alarm 4070 — Meaning Depends on Controller: Ambient temp. sensor circuit / Engine coolant temp sensor circuit

Common Symptoms

• Alarm 4070 shown on the Xc-series controller display
• Machine may shut down or refuse to load, depending on the alarm class

Probable Causes (Ranked by Likelihood)

• Depends on the controller fitted — see the per-controller meanings in the diagnostic steps High
• Sensor, switch or wiring fault in the monitored circuit producing a false alarm Moderate

Step-by-Step Diagnostic Procedure

1. Identify which Xc-series controller your machine has FIRST (Xc1004, Xc2003 or Xc4004 — it is named on the controller face or in the machine documentation). The same alarm number can mean different things on different controllers, so the controller identity is part of the diagnosis.

2. On Xc2003, Xc4004: alarm 4070 = Ambient temp. sensor circuit

3. On Xc1004: alarm 4070 = Engine coolant temp sensor circuit

4. Let the machine cool, then check coolant level and the cooler for blockage. Repeated trips with good coolant level point at the sensor or a genuine cooling-system fault, not something to reset past.

5. A circuit alarm means the controller lost a plausible signal — check the sensor connector and wiring for damage or corrosion before replacing the sensor itself.

6. This page is built from Atlas Copco's published Xc-series alarm table (linked below). For machine-specific procedures, use the manual for your exact unit — the table defines what the alarm is, not every model's repair steps.

Frequently Asked Questions