Tough O2 sensor?
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Cargo Master
Joined: Sep 2007
Posts: 2,095
Likes: 2
From: Wahpeton ND
Tough O2 sensor?
So I know that a HEGO has 4 pins
1-Ground
2-12V positive
3-HEGO
4-signal return
So I am assuming that the positve and ground are used to powwer the heater and the HEGO wire is the verification that it is operating?
The ground is also acting as the bias for the O2 reading that is returned to the PCM via the sig return wire?
I have a sensor fault of P0141 and P0155 which is a O2 sensor heater failure that is random and intermittant but constant even on new O2 sensors in my 96 F150.
I realise that this is not a crucial failure but it is a matter of pride not to be driving around with a idiot light on.
Anyone have a guess on which wire it may be?
1-Ground
2-12V positive
3-HEGO
4-signal return
So I am assuming that the positve and ground are used to powwer the heater and the HEGO wire is the verification that it is operating?
The ground is also acting as the bias for the O2 reading that is returned to the PCM via the sig return wire?
I have a sensor fault of P0141 and P0155 which is a O2 sensor heater failure that is random and intermittant but constant even on new O2 sensors in my 96 F150.
I realise that this is not a crucial failure but it is a matter of pride not to be driving around with a idiot light on.
Anyone have a guess on which wire it may be?
Lead Driver
Joined: Nov 2002
Posts: 9,558
Likes: 45
From: Concord, NC
The signal return is actually the sensor ground circuit for the computer (less noise than using the vehicle ground), and the HEGO wire is the signal. The signal return is shared with several other sensors - I'm not sure why Ford chose to name the circuit what they did. The heater is powered with a relay, so check the relay for proper operation, the fuse on the heater circuit, and check for a good heater ground.
Thread Starter
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Cargo Master
Joined: Sep 2007
Posts: 2,095
Likes: 2
From: Wahpeton ND
Which relay is it?
The fuse is OK and I can find no wires that are frayed or burnt. The grounding is done through the PCM if I aint mistaken.
Addmitdly I did not rip open the looms but as it is an intermitant issue I dought it is inside a loom.
The fuse is OK and I can find no wires that are frayed or burnt. The grounding is done through the PCM if I aint mistaken.
Addmitdly I did not rip open the looms but as it is an intermitant issue I dought it is inside a loom.
