I mentioned in a previous post that I planned to measure the voltage from the Lambda probe to the ECU this weekend. Well, I just have and have some interesting results.
From what I described in my earlier post, I believe the red wire illustrated in the picture above is the one from the Lambda sensor. It contains three wires, one red, one white and one black. The red wire I believe sends 12 volts to the heating element in the Lambda probe. The black and white wires send a voltage between 0 and 1 volts from the Lambda probe to the ECU to indicate whether the fuel mixture is lean or rich.
The wire connects to the ECU wiring loom via a 3 pin connector pictured above. After disconnecting the connection, I measured the voltage between the black and white pins from the Lambda sensor, but got 0 volts.
As way of a check, I measured the voltage across the red wire from the ECU and got about 12 volts, indicating that the ECU was at least trying to heat up the Lambda probe.
So it seems that my Lambda probe isn't working at all? Which would explain why my car failed the emissions test. It's a bit odd that I've not been getting a "check engine" light coming up on the dashboard though?
I'll have a chat with Jorrit at Auto Forza on Monday and maybe take the car 'round to the garage to check that there's no bad connections in the wire (or that it's broken anywhere).