Check Engine never comes on: P0650 and buying a car

This takes ten seconds and should be done before buying a car: turn the key without starting. If the Check Engine light did not come on with the others, it is not «fine» — it is simply gone.

When the ignition is switched on, every lamp on the dashboard must come on together and go out a couple of seconds later. That is not decoration but a designed self-check: it is how the driver sees the bulb is alive.

A Check Engine light that stays dark from the start means one of two things: either its circuit is broken, or it was removed on purpose.

What P0650 means

P0650 — malfunction indicator lamp circuit fault. The unit sends the «light up» command and sees no load on the output.

There are exactly three causes:

1. The bulb burned out or the dashboard LED failed — it happens, and it is honest wear.
2. An open circuit — rarer, usually after dashboard work.
3. Somebody took it out. The most common cause on high-mileage cars offered for sale.

Why this matters more than it seems

The lamp is the only way the car reports trouble to the driver. Without it, a car with any set of faults looks healthy: mixture, catalyst, misfires — all of it accumulates silently.

On the used market this is exploited directly. So when checking a car before buying, looking at the dashboard with the ignition on is worth doing before you take the adapter out — the same point is made in how to check a car before buying.

⚠️ And the other side: if you are selling, a removed bulb is not a trick but a reason for the buyer to walk away. What they will see and what is fairer to show yourself is in selling a car: what a buyer sees with a scanner and in what to show the buyer.

How to check it in the app in a minute

The app reads not the bulb itself but the state the bulb is supposed to show. And that is stronger than looking at the dashboard: a lamp can be removed, a state cannot be faked.

1. The fault list. If there are faults and the lamp never lit, you already know everything.
2. The «lamp on» flag. The unit reports it separately from the codes themselves. The unit says «on» and the dashboard is dark — the circuit, or a removed bulb.
3. Readiness of the self-tests. Every counter at zero at once means the battery was disconnected or the codes cleared very recently. Before a sale that is not usually done for nothing; in detail — readiness for the emissions test.

⚠️ Do not confuse this with another case: the lamp on but not flashing is one state, and flashing is quite another and far more urgent. The difference is in Check Engine flashing rather than steady.

And separately: silence from a module in response to a request is not «no faults». Why — in «no response».

What to do

1. Switch on the ignition and photograph the dashboard — that shows which lamps lit and which did not.
2. Read the codes and compare with what the dashboard showed.
3. Look at the self-test readiness: a fresh reset shows up immediately.
4. Replace the bulb or the LED if that is the cause — the part costs pennies.
5. Only then draw conclusions about the car itself: a fault can be active, stored or pending for various reasons.