MT4 Expert Advisor Not Trading? 10 Fixes (Error 4109, 0 and More)

Smart Algotrade — Sun, 15 Nov 2026 14:39:16 +0000

If your Expert Advisor (EA) is not trading, the good news is that the cause is almost never the EA itself. In most cases it is a single setting in MetaTrader 4, and you can find it in a couple of minutes. This guide walks through every common reason, starting with the fastest checks.

The short answer

Check these five things in order. Together they solve the large majority of cases:

The AutoTrading button in the toolbar is switched on.
The chart shows a smiley face, not a sad one, next to the EA name.
Allow live trading is ticked in the EA's settings.
The EA is attached to the right symbol and timeframe.
The Experts and Journal tabs show no errors.

If all five look right and it still does nothing, keep reading.

1. Check the smiley face first

When you attach an EA to a chart, MT4 shows its name in the corner of the chart with a small face next to it:

Smiley face: the EA is running and can trade.
Sad face: the EA is running but cannot trade.
No name at all: the EA is not attached, or it failed to load.

A sad face almost always points to one of the next two sections. No name at all usually means the file is in the wrong folder - see this step-by-step guide on how to install an Expert Advisor into MetaTrader 4.

2. The AutoTrading button is off

This is the most common reason. The AutoTrading button is a master switch for every EA in the terminal. When it is off, it shows red and every chart shows a sad face.

Click it once to switch it on - it should turn green. MT4 can switch it off again by itself when you change account or load a different profile. If it keeps turning off, open Tools → Options → Expert Advisors and untick the options that disable automated trading on those changes.

3. "Allow live trading" is not ticked

AutoTrading is the global switch; each EA also has its own permission. Right-click the chart, choose Expert Advisors → Properties, open the Common tab and tick Allow live trading.

If this box is empty, the EA runs but cannot place orders, and MT4 reports error 4109 in the Experts tab. While you are there, check the Long & Short setting - if it allows one direction only, the EA ignores every signal in the other.

To make this the default, tick Allow automated trading in Tools → Options → Expert Advisors.

4. Wrong chart, symbol or timeframe

Most EAs are built for specific pairs and a specific timeframe. On the wrong chart, the EA may wait forever because its conditions never occur. Running more than one EA? Give each its own chart - here is how to run multiple Expert Advisors on one MT4 account.

Watch out for symbol suffixes. Many brokers name pairs EURUSD.m, EURUSDpro or EURUSD-ECN. An EA that expects plain EURUSD may not recognise the symbol and never trade.

5. Market closed or no new tick

An EA's OnTick() runs only when a new price tick arrives. Attach it at the weekend or in a quiet holiday session and it will sit still until the market moves. That is normal, not a fault.

Also check the connection indicator in the bottom-right corner - it should show traffic, not No connection or Invalid account.

6. Read the Experts and Journal tabs

Open the Terminal window with Ctrl+T. Experts shows messages from the EA; Journal shows messages from the platform and the broker. The codes you are most likely to see (meanings from the MQL4 documentation):

Error	Meaning	What to check
0	Broker blocks automated trading	Ask broker support to enable EA trading
4109	Trade is not allowed	Allow live trading and AutoTrading
133	Trade is disabled	Account type or investor password
134	Not enough money	Free margin and lot size
131	Invalid trade volume	Lot below the minimum or wrong step
130	Invalid stops	SL or TP too close to price
132	Market is closed	Trading hours for that symbol
146	Trade context is busy	Too many EAs trading at once

If the tabs are silent, the EA is probably running normally and waiting for a signal.

7. Error 0: the broker blocked EA trading

The order fails with error 0 even though AutoTrading is green and the chart shows a smiley face. The problem is not in MT4 - the broker has blocked automated trading on your account.

Nothing in the terminal will fix it. Contact your broker's support, give them your account number, mention error 0, and ask them to enable automated (EA) trading.

8. Not enough margin or wrong lot size

If free margin is too low, the broker rejects the order with error 134 - common on small accounts after a few losses.

If the EA calculates a lot size below the minimum (usually 0.01) or off the broker's lot step, the order fails with error 131. A free MT4 lot size calculator script helps you check the right size, and this guide explains how much money you need to start algo trading.

9. Investor password or account type

MT4 accounts have two passwords. The master password allows trading; the investor password is read-only. Logged in with the investor password, every order fails with error 133. Log in again with the master password, and confirm with your broker that your account type allows automated trading.

10. Your computer went to sleep

An EA only works while MT4 is open and connected. If the computer sleeps, shuts down or loses internet, the EA stops. That is why traders who run EAs full-time use a low-cost VPS that stays online 24/7.

Can an EA run on the MT4 mobile app?

No. The MT4 apps for Android and iPhone do not run Expert Advisors. You can watch the trades, but the EA must run on the desktop terminal or a VPS.

When the EA is working but just not trading

Sometimes nothing is wrong: smiley face, AutoTrading green, clean tabs. The EA is simply waiting for its conditions. Some strategies trade several times a day; others wait days for a setup.

Check how often the EA normally trades by looking at its backtest - here is how to read an MT4 backtest report. If it hardly trades even in its own backtest, or the results look too good to be true, read why most Expert Advisors fail and how to spot a scam Expert Advisor.

Final thoughts

An EA that is not trading is rarely broken. Work through the checks in order: AutoTrading, the smiley face, Allow live trading, the chart, then the Experts and Journal tabs. Most problems end in the first two minutes.

Originally published on the Smart Algotrade Algo Trading Blog. Smart Algotrade develops automated Forex trading robots for MetaTrader 4.

Risk warning: Forex and CFD trading involves significant risk of loss.

DEV Community: Smart Algotrade