need to resolve this within 1hr P0141 - o2 sensor heater circuit malfunction It has 4 wires: Black - signal Red Heater (+) Yellow heater (-) White Ref. (in) Can I just join the red and yellow wire together to bypass the said heating element? Will that work as a temporary fix?? I'm assuming as the element heats up the resistance decreases so I'm just bypassing this??
Reason I ask is I used a universal sensor and believe I didn't crimp the red or yellow wire properly, I would like to bypass it asap.
I'm thinking no, no, and no. If you join those two wires you'll blow a fuse next time you start it up, I'd think. I imagine it would be a PTC-type heater, so the resistance would go up as it got hotter, so it self-stabilises at a particular temperature. Sorry, can't think of a quick fix, other than re-crimping the wires. Don't suppose you have any more crimps though. [:^(]
Hi I wonder which fuse will blow if you do that. Got a multimeter with crocodile clips? Measure the resistance of the heater circuit of the o2 sensor then use a resistor of the same value.
no crimps, trader is picking up the car tonight so you're saying that as the heater heats up, voltage should be reduced in the yellow wire? so giving the yellow a constant 12v from the red before even reaching the lambda would fail? I know it is a wiring fault so just want to bypass it. Does the positive do anything else at the lambda end?
My poor sketch: Will doing the above just mean the lambda will take longer to heat up? But the exhaust will heat it anyway? But no fault codes will be thrown up as a result?
Still guessing here, but I'd think the red wire will have a permanent (ignition on) 12v on it, and the yellow wire will go through something (shunt resistance?) in the ECU so that it knows what current is going to the heater (and so knowing if something is wrong to throw up the fault code), then to ground. The ECU will expect the current to be pretty big at first as the thing is cold, and to drop off fairly quickly as it heats up. Don't think you'll fool it with a short circuit or a fixed resistor. It will heat up just with the exhaust gases, as you say, but the ECU will still sense the fault, I'd think. Try disconnecting the wires and see?
Disconnecting the wires throws up the fault code immediately (obviously as it has a break) The above is simulating the poor connection elsewhere down the line
Run the engine 'til the zorsts nice and hot, then (carefully) measure the resistance across the heater+ and heater- wires that go into the sensor (you could measure this when cold too for comparison). Put a resistor of about that (hot) value on the ends of the wires that should be going to the heater. Might work by fooling the ECU that its up to temp, but it also might just burn the resistor out, depends what value and wattage the resistor is.
Don't bother trying to bodge or bypass anything. Pete's right that the ECU will have a very small shunt resistance in the ECU to monitor how much current is being drawn by the heater. The ECU will probably shut off lambda heater control if the current is above or below the expected range (including dead short or open circuit). The amount of current can be several amps. Don't bother trying to put a resistor in place to fool the ECU; you'd need a bloody hefty resistor. The lambda sensor won't work properly without the heater and I believe the sensor element will eventually be damaged without the heater operating.
