How to Read Graco Reactor 2 Error Codes: A Field Guide for Applicators

A Reactor 2 alarm always seems to show up at the worst moment: the truck is masked, the customer is waiting and the ADM is flashing four letters you have never seen. The good news is that Graco's codes follow a pattern. Once you can read it, most alarms tell you exactly where to look.

This guide covers the Reactor 2 electric (E-30, E-XP2) and hydraulic (H-30, H-40, H-50, H-XP2, H-XP3) units with the black ADM screen. The code meanings come from Graco's Reactor 2 repair manuals and Graco's online help pages.

Where Reactor 2 codes show up

When an error happens, the ADM opens an error screen with the active code and a short description. Graco sorts every event into one of three levels:

• Alarm: a critical condition. The system stops.
• Deviation: needs attention, but does not stop the system yet.
• Advisory: information that is not immediately critical.

Press the soft key next to "Help With This Error" to get a QR code that opens Graco's online troubleshooting for that code. Graco also says to identify the code before you reset it. If it already cleared, the Errors screen stores the last 200 errors with date, time and description.

How to read the four characters

Graco does not publish a character by character decoder, but its code list follows a clear pattern. Here is the shorthand our tech team uses. Treat it as a reading aid, and always confirm the exact code in the manual.

The last characters usually name the location. Codes ending in DA or DB point to heater A or B, DH to the heated hose, AX or BX to A or B outlet pressure, FA or FB to the A or B inlet (Elite sensors), NM to the motor, and CM or CT to the motor or temperature control module.

Pressure imbalance: P0AX, P0BX, P7AX, P7BX

These four mean the difference between A and B pressure went over the imbalance value set in System Setup. The "A" versions mean A is high, the "B" versions mean B is high. Graco lists the same checks for all four:

1. Fill empty drums and confirm the feed pumps are running with correct air pressure.
2. Check both supply hoses and inlet strainers for blockage.
3. Make sure both material lines have equal restriction all the way to the gun.
4. Review the imbalance value in System Setup. A value set too low trips early.
5. Look for fluid at the heater inlet rupture disk. If it leaked, clear the plugged heater or PRESSURE RELIEF/SPRAY valve and replace the disk. Graco says never replace it with a pipe plug.

Related pressure codes worth knowing: F9FA / F9FB is a flow cutback from low inlet pressure on that side, DADX is pump runaway (empty pumps, closed inlet valves or a mix chamber too large for the machine), and P4AX / P4BX is high pressure, often from pressurizing before the heaters reached setpoint.

T6, A8 and other heat codes

For hose sensor faults, Graco has you measure the cables with RTD test cables (24N365) against the values in the repair manual. To finish a job, you can unplug the hose RTD and run Hose Manual Mode, or Hose Resistance Mode if a calibration is saved. For the full hose walkthrough, see our guide to heated hose diagnosis on the blog.

Voltage and frequency codes

V codes (low or high voltage) and H codes (line frequency below 45 Hz or above 65 Hz) almost always point to supply power, not the Reactor. Graco's repair manual gives 195 to 264 VAC and 45 to 65 Hz as the range for the electric units. Check for loose wiring and tripped breakers, measure voltage at each breaker, and on a high-leg delta generator Graco calls for switching to 208 VAC wye. On the electric units, A4DH (high hose current) is also tied to voltage or frequency swings and undersized generators.

What to check first, every time

1. Write down the code and whether it is an alarm, deviation or advisory.
2. Check the easy stuff: drum levels, feed pump air, inlet valves open, breakers set.
3. Walk the connections the code points to: RTD plugs, hose connectors, the whip.
4. Use the ADM help QR code or the Graco manual for the exact test values.
5. Only then order parts.

Our interactive equipment troubleshooter does this for you: pick your Reactor, enter the code, answer a few guided checks and get the likely cause, fix steps and exact part numbers. Parts like RTD cables and Power-Lock splice kits are in Parts and Rebuild Kits, and approved applicators see their account pricing through the Applicator Program.