Fix ECI M1 MRP Suggestions That Look Wrong
ECI M1 MRP suggestions wrong or missing shortages
Also searched as
- ECI M1 MRP not showing shortages
- M1 ERP MRP suggests wrong order quantity
- ECI M1 planning parameters lead time
- M1 MRP run results not what I expected
Short answer
When MRP in M1 suggests the wrong quantity or misses a shortage, the cause is almost never the calculation. It is the inputs: item planning parameters, lead times, BOM structure, inaccurate on-hand or open order data, or a planning run that was not complete. Check those in that order.
Applies to: ECI M1 ERP for discrete manufacturers; planning screen and parameter names vary by version, so verify against your own system
How to troubleshoot MRP results in M1
- 1Pick one specific item where the result looks wrong and work only on it, rather than reviewing the whole plan.
- 2Check the item's planning data: planning method, order policy, safety stock, minimum and multiple order quantities, and whether it is flagged to be planned at all.
- 3Verify the lead time on the item, and the supplier lead time if purchased, because a short lead time makes MRP place orders too late.
- 4Review the BOM that drives demand: confirm the quantity per, scrap factor, effectivity dates and that the component sits under the parent you expect.
- 5Compare on-hand with a physical count for the item; check for stock sitting in a location that MRP excludes or flagged as non-nettable.
- 6Examine open sales, work and purchase orders for the item for stale, mis-dated or already-closed documents still counted as supply or demand.
- 7Confirm the MRP run was a full regeneration and not a partial or net change run that skipped the item.
- 8Rerun for the item, compare the new suggestion with your manual calculation, and fix the root input instead of overriding the suggestion.
MRP is arithmetic on your data
MRP takes gross requirements from sales orders, forecasts and parent demand, subtracts on-hand and scheduled receipts, applies the order policy, and offsets the result by lead time to date the suggestion. If any input is wrong, the output is wrong with perfect consistency. That is why a single traced item usually reveals the fault in minutes.
Write the calculation out by hand for your problem item: gross demand by week, minus supply, equals net need. Compare each week with what M1 shows. The first week where the numbers diverge is where the bad input lives.
Planning parameters that quietly change results
Order policy produces many surprises. A lot-for-lot item behaves very differently from one with a minimum order quantity, an order multiple or a fixed period. If a purchased item has a large minimum, MRP will suggest it even for a small need, and the suggestion is correct by design.
Safety stock and lead time are the other two. A safety stock that no longer reflects reality creates early or oversized suggestions. A lead time that was entered years ago and never revisited will date every purchase too late, producing shortages that MRP appears to ignore.
Data errors that hide shortages
Missing shortages usually trace to supply that is not real. A purchase order past its due date, a work order with a quantity that was never closed out, or on-hand that is inflated because scrapped stock was never adjusted will all satisfy demand in the plan while the shelf is empty.
BOM structure errors do the opposite for demand. A component missing from the BOM never appears in MRP at all, and an item entered at the wrong level can be netted before its demand arrives. Audit the BOM for the parent that drives the failing item.
Hand-check template for one item: Week Gross Scheduled receipts Projected on hand Net need Planned order wk 1 ... ... ... ... ... First week that differs from the M1 screen = location of the bad input.
Run settings and process habits
A net change run only recalculates items whose data changed, which is fast but can leave a stale result if a change was not flagged. When results look inexplicable, run a full regeneration at a quiet time and compare. If the full run fixes it, your net change process is missing an update trigger.
Finally, agree on who reviews and releases suggestions. Planners who routinely override MRP to compensate for bad lead times or counts erode trust in the system. Fix the data when you find it, and the plan becomes something the shop can rely on.
Common pitfalls
- !Overriding suggestions repeatedly instead of correcting the lead time or count that caused them.
- !Leaving stale purchase orders or work orders open so they count as supply.
- !Assuming the minimum order quantity or multiple is a bug when it is a planning parameter.
- !Running only net change planning when the data was changed in ways that do not trigger recalculation.
- !Forgetting that stock in a non-nettable location is excluded from the net calculation.
How an ERP-grounded AI assistant handles this
Tracing one item through demand, supply and parameters is where an assistant helps most. Grounded in your M1 data, it can show gross requirements, open orders and planning parameters side by side, point out the stale order or the lead time that explains the result, and show the query it ran. It reads the data and leaves changes to your planners.
Frequently asked questions
Why does MRP suggest a quantity bigger than I need?
Most often the item has a minimum order quantity, an order multiple or a safety stock that raises the suggestion. Check the item's planning parameters before assuming an error. The suggestion may be exactly what the policy tells MRP to do.
Why is a shortage not appearing in MRP?
Usually because something counted as supply that is not real, such as a past-due purchase order or an inflated on-hand balance. Compare the physical count with the system and review open orders for stale entries.
Should I run net change or regeneration?
Net change is faster for routine use, while a full regeneration recalculates everything and is the safer choice when results look wrong. If regeneration changes the plan, investigate why net change missed it.
Can lead time errors cause missed deliveries?
Yes. MRP offsets a need by the stored lead time, so a lead time shorter than reality dates purchases too late. Review supplier lead times against actual receipt history at least once a year.
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