Controller to ECM CAN Communication Lost
The ATLAS-COPCO-E070 (Xc4002 / Xc2003 / Xc4004 Controller) diesel fault code means: Controller to ECM CAN Communication Lost. This is a serious severity code.
- Keep driving?
- No -- stop driving
- DIY difficulty
- moderate
- Estimated cost
- DIY wiring repair $10-$80 (connectors, terminals, termination resistor). Professional diagnosis and harness repair $150-$400. ECM replacement $800-$2,500 depending on engine platform. Controller replacement or reprogramming $500-$1,500 at an Atlas Copco dealer.
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Common Symptoms
- Panel displays E070 and the yellow or red alarm LED comes on
- Compressor starts but immediately shuts down or refuses to load
- Engine RPM gauge on the Xc4002 / Xc2003 / Xc4004 controller LCD reads zero or dashes even while engine is running
- No engine fault codes appear in DiagPro even though engine protection is active
- Engine derate or low-power condition with no other obvious cause shown on the display
- RUN mode selected but unit will not accept air demand or build pressure normally
- CAN bus error message appears alongside E070 on the controller LCD side panel
Probable Causes (Ranked by Likelihood)
- Damaged, corroded, or unplugged CAN bus connector between the controller and engine ECM Very Likely
- Broken or shorted CAN High / CAN Low wiring in the engine harness, especially near heat sources or pinch points Very Likely
- Missing or failed 120-ohm CAN termination resistor at one end of the J1939 bus Likely
- Engine ECM has lost power or ground, preventing it from transmitting on the CAN bus Likely
- Controller firmware mismatch or corrupted parameter set after a failed software update Possible
- Faulty or failed engine ECM that is no longer broadcasting J1939 messages Possible
- Electrical interference from a damaged alternator, solenoid, or nearby welding equipment corrupting the CAN signal Less Likely
Step-by-Step Diagnostic Procedure
Step 1 -- Check the obvious first. Turn the unit OFF, let it sit 30 seconds, then restart. A single power cycle clears transient CAN dropouts. If E070 returns within a minute, keep going.
Step 2 -- Inspect all CAN bus connectors between the Xc4002 / Xc2003 / Xc4004 controller and the engine ECM. Look for bent pins, corrosion (green or white residue), mud, or water intrusion. Unplug each connector, blow it out, and reseat it firmly.
Step 3 -- Trace the J1939 harness from the controller to the ECM. Look for chafed insulation, pinched wires against frame rails or hot exhaust components, or any spot where a wire has been cut or spliced. Repair any damage found.
Step 4 -- Measure CAN bus resistance. With the unit OFF and both connectors unplugged from the ECM and controller, put your multimeter across the CAN High and CAN Low wires at the midpoint of the harness. You should read 60 ohms (two 120-ohm termination resistors in parallel). A reading above 120 ohms means a termination resistor is open or missing. A reading near 0 ohms means CAN High and CAN Low are shorted together.
Step 5 -- Verify ECM power and ground. With the key in RUN and a multimeter, check that the engine ECM has battery voltage (typically 12 VDC on Kubota platforms, 24 VDC on Deutz and CAT platforms) on its supply pins and a solid ground. A missing ECM ground is a common cause of a silent CAN bus.
Step 6 -- Connect DiagPro via the J1939 / CAN data port on the control panel. Check whether DiagPro can see the engine ECM at all. If DiagPro also shows no ECM, the fault is in the wiring or the ECM itself. If DiagPro sees the ECM but the panel still shows E070, suspect the internal controller CAN port or a parameter mismatch.
Step 7 -- If wiring and power check out, swap the 120-ohm termination resistor (usually a small plug-in resistor at the controller end of the CAN harness). This is a cheap, common wear item and takes less than five minutes to replace.
Step 8 -- If E070 persists after all wiring and resistor checks, the engine ECM or the controller itself may need replacement or reprogramming. This step requires Atlas Copco DiagPro with a valid license and controller access codes. Contact Atlas Copco service or a qualified dealer.
Frequently Asked Questions
What does Atlas Copco code E070 mean?
E070 means the Xc4002 / Xc2003 / Xc4004 controller on your compressor has lost its CAN communication link to the engine ECM. The controller uses that J1939 data link to read engine speed, temperatures, pressures, and active fault codes. When that link goes down, the controller cannot safely manage the engine, so it shuts the unit down or blocks loading.
Can the compressor still run with E070 active?
No. E070 is a protective shutdown. The controller will not allow the unit to operate under load without confirmed ECM communication because engine protection, derate logic, and fault monitoring are all blind. You need to clear the root cause before returning the unit to service.
How much does it cost to fix E070?
If the fix is a dirty connector or a failed termination resistor, you are looking at under $80 in parts and an hour of your time. A harness repair at a shop runs $150-$400. If the engine ECM has failed, budget $800-$2,500 for the part depending on whether it is a Kubota, Deutz, or CAT platform. Controller-side issues requiring reprogramming add another $500-$1,500.
Is E070 always a wiring problem?
Most of the time, yes. The large majority of E070 faults trace back to a corroded connector, a chafed wire, or a missing termination resistor. Actual ECM or controller failures do happen but are much less common. Start with the wiring and termination resistor before assuming you need new electronics.