Thank you “valvestation”, I found the connectors you mentioned. The connector supplying voltage for heater is good and the heater has resistant about 4 ohm. However, the connector for lambda signal (+ black wire and – grey wire) has been cut & splice
. When I check the wiring, I found that those two wires is incorrect spliced so the signal send to the ECU is reversed in polarity
. The wires from lambda connector to ECU have black color for – and green color for + signal. The one who did this confused with the color of the wire! The black one from ECU is ground but the black one from sensor is the signal. So I fixed it to correct polarity. Is it possible that the wrong connection have ruined the ECU already so it gave 1-2-2-3 code?
Then I check the signal with multimeter (VDC) the voltage across these two wires is quite low ~0.1-0.4 V and never rise higher. The wiring from the connector to ECU in the car is good. Do I need to replace the sensor, is it a faulty sensor?
If I have to replace it, the part number for Bosch sensor from catalog is 0258003301 (direct fit) and 0258986506 (universal fit). The two sensors should be the same. All I need to do is just splice the wire myself and the price for universal is about half of the other. Should I go with the universal one?
Thank you all for suggestion.