MTN Troubleshooting Codes: Fix Common USSD Errors

Last Updated: November 2025
Disclaimer: nigeriaussdcodes.com is an independent educational website. We are not affiliated with MTN Nigeria or the NCC. All information here is verified through official MTN and NCC channels.*

Why MTN USSD Errors Happen

USSD (Unstructured Supplementary Service Data) remains one of the fastest, data-free ways to manage MTN services — recharge, check balance, buy data, borrow credit, or link your NIN.

But even though it works without internet, many users still experience annoying errors such as:

• “Invalid MMI code”

• “Connection problem or invalid MMI”

• “Session timed out”

• “Service not available”

• “Please try again later”

• “SIM not responding”

These are not strange issues — they happen because of signal problems, temporary server downtime, or wrong SIM selection.

This 2025 guide explains every common MTN USSD error, why it happens, and how to fix it instantly — step by step.

Quick MTN USSD Codes

All these codes are harmonized by the Nigerian Communications Commission (NCC) and work on every MTN SIM.

“Invalid MMI Code” or “Connection Problem”

Meaning

Your phone cannot process the USSD command properly.

Causes

• Weak or no MTN signal.

• SIM toolkit not responding.

• Wrong SIM selected (dual-SIM phones).

• Temporary network downtime.

Fix

Confirm MTN SIM is active for calls/USSD.
Turn on Airplane mode for 10 seconds → then turn it off.
Restart your phone.
Try dialing the code again.
If it persists, dial with a semicolon — for example:
 *310#; — this forces the dialer to treat it as a USSD.

Example:
A user in Lagos couldn’t recharge using 311PIN#, but after reselecting SIM 2 (MTN) as default for calls, it worked instantly.

“Session Timed Out”

Meaning

Your phone took too long to respond, or MTN’s server closed the session.

Causes

• Delayed response in multi-step menus.

• Network congestion (evenings or holidays).

• Weak 4G/3G signal.

• Slow phone performance.

Fix

Dial again and respond quickly (within 10 seconds).
Move to an area with stronger MTN signal.
Close all background apps (especially data-heavy ones).
Use direct short codes instead of going through menus.

Example:
Instead of navigating 312# → 1 → 2 → 1, dial 312121# directly to buy your plan instantly.

“Service Not Available” or Blank Screen

Meaning

The MTN USSD service is temporarily offline or your SIM isn’t fully registered.

Causes

• Temporary outage.

• Unlinked NIN or incomplete SIM registration.

• Device dialer error.

Fix

• Restart your phone.

• Dial *996# to confirm NIN linkage.

• Try again in 5–10 minutes.

• If persistent, test your SIM in another phone.

Note:
New SIMs might take 24–48 hours before full USSD functions become active.

Airtime Recharge Errors

Common Messages

• “Incorrect PIN.”

• “PIN already used.”

• “Recharge failed, try later.”

Fix

Confirm you typed all digits correctly.
Wait 2–3 minutes and redial 310# to refresh balance.
If it says “PIN used,” call MTN on 300# and provide the recharge card serial number.
For ePIN or VTU errors, screenshot transaction and contact your vendor.

Tip: Always buy recharge from verified POS or app vendors (MTN On-Demand, myMTN App).

“Network Error” / “No Response”

Causes

• Poor 4G signal (common indoors).

• Temporary disconnection from network tower.

• SIM interference in dual-slot phones.

Fix

Move outdoors or near a window.
Switch network mode:
 Go to Settings → Mobile Network → Preferred Network → select “3G only.”
Dial *310# again.

If this works, your 4G network might be congested; switch back after a few minutes.

BorrowMe (Airtime/Data) Not Working

Meaning

MTN is restricting your borrow eligibility.

Causes

• Not enough recharge activity.

• Unpaid previous loan.

• SIM is new (needs usage history).

Fix

Dial *303# again after 24 hours.
Recharge ₦200–₦500 consistently for 1–2 weeks.
Repay old BorrowMe balance.
Keep line active (make calls, browse, or send SMS).

Example:
A user in Benin started getting “You are not eligible” after 6 months of inactivity. Eligibility returned after 10 days of consistent recharge.

Data Plan Activation Error

Causes

• Insufficient balance.

• Temporary MTN data system delay.

• Outdated SIM toolkit settings.

Fix

• Confirm airtime with 310#.

• Retry via 312# or use 31211#.

• Restart phone and wait 2–3 minutes.

• Check confirmation SMS — sometimes the plan activates but doesn’t show immediately.

“Data Balance Not Available”

Causes

• Using bonus data or social data not tracked under main balance.

• Delay in SMS notification.

Fix

Dial both *323# and 3234# for full breakdown.
Check SMS inbox for “Bundle Activation” message.
Restart phone.

“You Have No Active Bundle”

Even though you just subscribed, MTN sometimes sends this message.

What to Do

• Confirm plan type (Night plan may only work between 11 pm–6 am).

• If purchased with bonus, wait 5 minutes or check 323#.

• If still not working, call 300# → Option 2 → Data Support.

SIM Toolkit or USSD Crashes

Causes

• Damaged SIM toolkit cache.

• Outdated dialer app.

Fix

Settings → Apps → SIM Toolkit → Clear cache/data → Restart phone.
If error persists, remove and reinsert SIM.

NIN Linking Errors

Causes

• NIN entry mismatch.

• Server downtime.

Fix

Dial *996# and follow on-screen prompts.
Verify your NIN via *346#.
If rejected, visit any MTN service centre for assistance.

Tip: NIN linkage is mandatory — unresolved linkage may cause USSD services to fail.

Real-World Examples

General Tips for Smooth MTN USSD Experience

Always use your MTN SIM slot for USSD commands.
Recharge frequently to keep SIM active.
Avoid dialing codes during network peak (6–10 PM).
Clear SIM Toolkit cache monthly.
Confirm NIN is linked and active.
Avoid using VPN during USSD transactions.

Frequently Asked Questions (FAQs)

Why does MTN USSD fail in my area?

Network congestion or tower maintenance. Move to an open area or retry after 10 minutes.

What should I do if my MTN code shows “invalid MMI”?

Ensure you’re using the right SIM slot and have strong signal. Restart or use the semicolon trick.

Can I use USSD codes while abroad?

Yes, if roaming is active. Otherwise, use the myMTN App or web portal.

Why does *303# say “not eligible”?

Your line needs consistent recharge and activity. BorrowMe eligibility updates weekly.

How do I check my data bonus separately?

Dial 3234# to view main + bonus data breakdown.

My NIN code keeps failing — what do I do?

Try *996# at night or use MTN’s official NIN linking portal (nin.mtn.ng).

Can I fix “Service not available” by myself?

Yes — restart your phone, reselect network manually, and check NIN linkage.

Why do I get “Session expired” after choosing a plan?

You’re responding too slowly or network is busy. Redial quickly or use the direct code.

How do I contact MTN if all codes fail?

Call *300#, use @MTN180 on X (Twitter), or visit the nearest MTN outlet.

How often should I clear SIM Toolkit cache?

At least once a month to prevent USSD freezing and “app not responding” issues.

Conclusion

MTN’s USSD codes are fast, reliable, and easy to use — but they rely on network stability and correct input.
Most USSD issues are temporary and can be fixed in minutes by:

• Restarting your phone

• Using the correct SIM slot

• Checking your NIN linkage

• Dialing codes during off-peak hours

Keep this guide saved — it will help you solve most MTN USSD problems without calling customer care.