A fault code doesn’t yet mean the unit or sensor itself is faulty: often it’s the plug and connector leading to it.
Possible causes
- Open bus wire: broken, chafed through or corroded away in a connector
- A connector of one of the units on the bus: corrosion, water ingress, not fully seated
- An incorrectly connected alarm, GPS tracker or other add-on equipment
What you can do yourself
- Check the battery and terminals: at low voltage control units lose communication.
- Write the codes down, clear them and check again: after a flat battery, a repair or voltage spikes, codes that are no longer current stay in memory.
- Think about what happened before the code: an engine wash, water in the cabin, an accident, body repair, an alarm installation — start inspecting the connectors and wiring there.
- If you have a multimeter, measure the CAN resistance at the OBD port between CAN-H and CAN-L with the ignition off and the battery disconnected: about 60 Ω is normal, 120 Ω means one line is open, 0–10 Ω means a short.
Stop and don’t drive on if:
- The instrument panel went dark or many warning lights came on at once
- Power steering is gone or the brakes don’t work as usual
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.
OOleg’s tip: don’t pressure-wash the engine
Never wash the engine with a Kärcher (a pressure washer), steam or anything like that — there’s a special foam cleaner for that. Once the rubber seals in the connectors have dried out, moisture gets inside and the sensor connectors and the computer (ECU) connector rot.
On Oleg’s website:Car wiring repair ↗
The explanation comes from the error code reference in the AvtoElektrik PRO app.