CEL/Engine Light P0030 O2 Sensor Fault

[akeizm]

Hi all,

I've been searching for a while and trying to fix this issue but basically I have a 2004 2.5 N/A Liberty that's got an error code of P0030. The code is H02S Heater Control Circuit (Bank 1 Sensor 1) fault which then I went out an replaced the O2 sensor (non genuine) and cleared the error code using Torque for Android Phones yet the fault keep re-appearing.

I'm unsure of which pin is which on the plugs but I did some tests using my multimeter and found when looking at the socket (the male plug that's apart of the main engine harness, not the plug on the sensor itself) the lower left pin has 12V on it so I'm assuming this is the 12V supply to the heater circuit. I've also checked the resistance of the heating element (put the multimeter across the 2 lower pins on the female plug. This is the plug on the sensor) and it showed around 5.3 ohms.

So from what I can see is I have 12V to the heating element and the heating element shows a resistance that I have read elsewhere is correct. What other tests can I perform to try and rectify the problem? From what I can see there doesn't look like any breaks in the wires.

And I'm checking the sensor that's nearest to the engine (in the exhaust near the drivers side headlight) and not the one that's on the inlet to the CAT. If I am checking the wrong sensor then I'm a complete idiot.

Thanks, Marc.

[bigBADbenny]

viewtopic.php?f=15&t=26262
Got the FSM?
Might be a way to make sure you're checking the correct sensors and harnesses

[akeizm]

Big,

I sure have. I know I'm getting 12v onto the hot wire on the heating element as I nicked the insulation on the wire and tested for voltage. I'm going to double check all the wires again and make sure the plug was assembled correctly but at this point in time I'm at a loss as to why it won't reset. Only things I can think of at the moment are another dud sensor or damage to the heating element circuit somehow (internal damage on the ECU). The car only has 120,000k's on it.

[akeizm]

Well reading the FSM again, it says to check resistance across pins 3/ 4 (which are the 2 lower pins I was talking about) and it says the resistance should be 2.4 ohms. My last reading was 5.3 ohms so maybe the sensor is a dud (if the ECU is that finicky about the resistance of the heater circuit), I'll have to check it again. Sigh more money to spend now.

[Ako555]

Hi
I stumbled upon this forum whilst searching for the same issue. Just wondering if you solved the problem and if so how? Is it the o2 sensor closest to the front right headlight near air filter?