A fault code doesn’t yet mean the unit or sensor itself is faulty: often it’s the plug and connector leading to it.
OOleg’s tip: no 5 volts — don’t rush to replace the unit
When the computer won’t communicate or there are no 5 volts, it’s not necessarily the computer itself: 5-volt sensors can drag down the 5-volt line, and because of that the computer won’t even switch on.
Disconnect the 5-volt sensors one at a time (pressure, throttle and accelerator pedal position, camshaft, fuel pressure) and see whether the 5 volts and communication come back. A shorted sensor or its wire is to blame.
Possible causes
- One of the sensors on this circuit is shorted
- Wiring
- ECU (rarely)
What you can do yourself
- Unplug the sensors one by one: when the code disappears, you’ve found the culprit.
Stop and don’t drive on if:
- The Check Engine light is flashing
- The temperature gauge is in the red or the overheating light is on
- The red oil pressure light is on
- Smoke from under the bonnet, a burning or petrol smell
- Strong jerking, knocking from the engine, or the car barely moves
OOleg’s tip: check the connector
Often the cause is simple — there is no contact in the connector (plug). Look at the connector from the back: remove the rubber seal and you will see whether a wire is corroded or has come off completely. Corrosion shows up as green deposits. Ideally, gently pull each wire towards you one at a time: a sound wire stays in place, while a corroded one simply comes off — it needs to be repaired.
Unplug and inspect connectors with the ignition off.
On Oleg’s website:Car computer diagnostics ↗
The explanation comes from the error code reference in the AvtoElektrik PRO app.