The car has obviously got wind that it is being sold and threw up a P0135 MIL.... This seems to point to the Pre cat O2 sensor which I guess will have to be replaced... Is there any way of testing this to make sure it is defective? In case there is a short somewhere etc? I cleared it but it came back so must be a fault somewhere...
Cheers.
P0135 - O2 sensor MIL
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Stumpy Nugget
- Posts: 206
- Joined: Thu Mar 19, 2009 9:44 pm
- Location: Elderslie.
P0135 - O2 sensor MIL
Polo Blue motion - Eco Warrior Spec
2001 Maroon S2. Loud money pit spec.
2001 Maroon S2. Loud money pit spec.
Re: P0135 - O2 sensor MIL
P0135 is the heater circuit rather than the actual O2 sensor (though they are integrated into the same package and cannot be replaced independently).
Split the O2 sensor plug apart and check for corrosion in the plug.
Also check the resistance of the heater circuit with the plug split (you're measuring the resistance of the heater in the O2 sensor so make sure you connect the probes to the O2 sensor plug and not the other part that leads back to the ECU).
You can tell which pair of wires are the heater circuit - they are thicker diameter than the other two; also they are probably grey.
If you get something about 6 ohms when the engine is cold you're OK and need to look for faults back towards the ECU.
If you get open circuit (i.e. the same as when the multimeter probes aren't touching anything) or short circuit (<1 ohm) then the sensor needs to be replaced.
Cheers,
Robin
Split the O2 sensor plug apart and check for corrosion in the plug.
Also check the resistance of the heater circuit with the plug split (you're measuring the resistance of the heater in the O2 sensor so make sure you connect the probes to the O2 sensor plug and not the other part that leads back to the ECU).
You can tell which pair of wires are the heater circuit - they are thicker diameter than the other two; also they are probably grey.
If you get something about 6 ohms when the engine is cold you're OK and need to look for faults back towards the ECU.
If you get open circuit (i.e. the same as when the multimeter probes aren't touching anything) or short circuit (<1 ohm) then the sensor needs to be replaced.
Cheers,
Robin
I is in your loomz nibblin ur wirez
#bemoretut
#bemoretut
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Stumpy Nugget
- Posts: 206
- Joined: Thu Mar 19, 2009 9:44 pm
- Location: Elderslie.
Re: P0135 - O2 sensor MIL
I had a quick go and seemed to hit about 9.8 ohm? Is this close enough to the 6 ohms you were referring to? or should it be spot on 6 ohms?
Polo Blue motion - Eco Warrior Spec
2001 Maroon S2. Loud money pit spec.
2001 Maroon S2. Loud money pit spec.
Re: P0135 - O2 sensor MIL
What's your meter read when you short the probes together?
At 6 ohms the heater will dissipate around 24 watts.
At 9.8 ohms the heater will dissipate only 15 watts.
However, the error code on the ECU is triggered by a short or open circuit condition and 9.8 ohms is neither of those. Was there any corrosion in the connector?
Perhaps as the heater heats up it goes open/short circuit?
Anyway, if there is nothing obvious wrong with the cabling the chances are the sensor itself will be at fault.
Cheers,
Robin
At 6 ohms the heater will dissipate around 24 watts.
At 9.8 ohms the heater will dissipate only 15 watts.
However, the error code on the ECU is triggered by a short or open circuit condition and 9.8 ohms is neither of those. Was there any corrosion in the connector?
Perhaps as the heater heats up it goes open/short circuit?
Anyway, if there is nothing obvious wrong with the cabling the chances are the sensor itself will be at fault.
Cheers,
Robin
I is in your loomz nibblin ur wirez
#bemoretut
#bemoretut
-
Stumpy Nugget
- Posts: 206
- Joined: Thu Mar 19, 2009 9:44 pm
- Location: Elderslie.
Re: P0135 - O2 sensor MIL
Robin, as ever great help... Basically the cables look good, connector looks clean (no corrosion).. My head says its the sensor but the way this car has been recently I am sure it is something totally different... 
Trying to find out if AA parts and labour will cover this as I need it fixed asap...
UPDATE: Looks like there is damage to the cable outer from the sensor to the connector, it looks as though it has been damaged by the manifold heat shield or something.. could be the problem, but as usual no bloody space to see it correctly.
Trying to find out if AA parts and labour will cover this as I need it fixed asap...
UPDATE: Looks like there is damage to the cable outer from the sensor to the connector, it looks as though it has been damaged by the manifold heat shield or something.. could be the problem, but as usual no bloody space to see it correctly.
Polo Blue motion - Eco Warrior Spec
2001 Maroon S2. Loud money pit spec.
2001 Maroon S2. Loud money pit spec.
Re: P0135 - O2 sensor MIL
Yes, if there's a nick in the insulation you could get moisture in there which in turns causes the cable to corrode and break; so whilst you've got 10 ohms with no load on the heater circuit you might have 1000 ohms once it tries to pass a significant current.
Cheers,
Robin
Cheers,
Robin
I is in your loomz nibblin ur wirez
#bemoretut
#bemoretut