FAQ
TL;DR: For MAN Euro 6 2014 (440), NOx 5556 often traces to a restricted AdBlue return; the fix kit costs about 500 PLN, and “Return hose to be replaced.” Replace/clean, then clear faults. This FAQ helps owner‑operators diagnose EDC/NOx after AdBlue cleaning. [Elektroda, mariomalinie, post #17290465]
Why it matters: Solving the root cause prevents derates, fines, and repeat roadside resets.
Quick Facts
- NOx 5556 commonly indicates a blocked AdBlue return line; confirm with a scan. [Elektroda, darfur5, post #17105935]
- Typical parts cost: Approx. 500 PLN for the MAN return hose kit with tips. [Elektroda, mariomalinie, post #17290465]
- If the injector is clogged, replace it; washing isn’t effective on Euro 6 dosing. [Elektroda, kakibara, post #17107339]
- Thorough urea‑hose cleaning restored line patency for one owner without upsizing the hose. [Elektroda, szyniu, post #17414312]
- After hardware repair, clear fault memory; unresolved codes may persist until reset. [Elektroda, kakibara, post #17298487]
What does NOx 5556 mean on a MAN Euro 6?
It points to a blocked or restricted AdBlue return line. Investigate for crystallization or a constricted hose, then repair accordingly. [Elektroda, darfur5, post #17105935]
How do I fix NOx 5556 after AdBlue system cleaning?
Replace the return hose if restricted, then reset faults. If the injector is clogged, address it after checking live parameters.
- Replace the return hose/cable.
- Reset errors with a diagnostic tool.
- Check injector parameters; replace if clogged. [Elektroda, kakibara, post #17298487]
Do I need to clear codes after replacing the return hose?
Yes. After replacing the hose, clear the fault memory with a diagnostic tool to complete the repair and restore dosing. [Elektroda, kakibara, post #17298487]
Why does the fault appear only when the truck is heavily loaded?
Drivers reported the fault shows up above 15 tons but not when lighter. Use that condition to reproduce and diagnose. [Elektroda, szyniu, post #17136908]
Is a larger‑diameter return hose necessary to solve 5556?
If errors continue after injector replacement, fit a larger‑diameter return hose as the next step in the repair. [Elektroda, kakibara, post #17107339]
How much is the MAN return hose kit and what do you get?
Approx. 500 PLN from MAN buys a complete return hose kit with the correct tips for a straightforward swap. [Elektroda, mariomalinie, post #17290465]
Will clearing the code without repairing anything work?
No. One driver cleared the code, drove about 400 km, and still needed the repair afterward. Fix the cause first. [Elektroda, telekawa, post #17299096]
Can cleaning alone fix NOx 5556 on a MAN E6?
Yes, if blockage is due to AdBlue crystals. Thoroughly cleaning urea hoses and the nozzle restored patency in one case. [Elektroda, szyniu, post #17414312]
Does injector washing help on Euro 6 dosing systems?
No. Replace the dosing injector if it is clogged. Washing does not resolve this on Euro 6 systems. [Elektroda, kakibara, post #17107339]
I replaced the return hose and 5556 came back—what next?
Check injector health and live dosing parameters. “This error can also be displayed when the injector is clogged.” Replace if needed. [Elektroda, kakibara, post #17298487]
I read EDC 45467—could it be 4467 instead?
Verify with a proper scanner. One post links EDC 4467 to a sudden temperature change in the AdBlue tank. [Elektroda, darfur5, post #17105935]
Which tool confirms a “return line blocked” message?
Use a diagnostic computer to read and describe the fault. Users reported scanners flagging the return line as blocked. [Elektroda, telekawa, post #17289915]
