CEL - Low rev hesitation again BACK AGAIN
05-10-2007, 10:55 AM
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CEL - Low rev hesitation again BACK AGAIN
Back in March I had to replace my o2 sensor (in the manifold) as it was dead. Athough it never gave me a CEL, fuel consumption went up and driving at low revs resulted in hesitation and kangoorooing. With help from DBM it was traced to a dead O2 sensor, which was replaced, and up until recently everything was fine.
However I have noticed a couple of times a slight hesitation at low revs again, espically if the engine was already warm and had been standing for a couple of hours. It wouldn't happen all the time, and I couldn't think of what might be causing it, and in truth I was hoping it would go away which was probably a silly thing to do. However, on Monday my car finally posted up a CEL on the dash, and with the aid of a ECU code reader (Cheers Mark) I got the error code this morning.
P0131 - Primary Heated Oxygen Sensor (Primary HO2S) (Sensor 1) Circuit Low Voltage.
I've been pm'ing DBM about this, and he's a little unsure what could be causing this and it's a bit unfair to rely on one person to bail me out, so I thought I'd throw it open to the forum.
Can anyone remember this thread Mark mentions above?
I'm very keen to get this sorted before Rockingham on the 20th, as I don't like the idea of raging a car with a CEL up. If nothing else this hesitation it will only spoil my fun, so any help would be much appriated.
However I have noticed a couple of times a slight hesitation at low revs again, espically if the engine was already warm and had been standing for a couple of hours. It wouldn't happen all the time, and I couldn't think of what might be causing it, and in truth I was hoping it would go away which was probably a silly thing to do. However, on Monday my car finally posted up a CEL on the dash, and with the aid of a ECU code reader (Cheers Mark) I got the error code this morning.
P0131 - Primary Heated Oxygen Sensor (Primary HO2S) (Sensor 1) Circuit Low Voltage.
I've been pm'ing DBM about this, and he's a little unsure what could be causing this and it's a bit unfair to rely on one person to bail me out, so I thought I'd throw it open to the forum.
Its either the sensor, an earth, or some other electrical fault in the system. Not convinced its the sensor. Something in the back of my head tells me someone had some issues with the wiring back to the ECU being dodgy (under the car) and causing the same thing you have, but I have no idea where the thread is...
I'm very keen to get this sorted before Rockingham on the 20th, as I don't like the idea of raging a car with a CEL up. If nothing else this hesitation it will only spoil my fun, so any help would be much appriated.
05-10-2007, 12:36 PM
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Hi Jamie, you will be ok on track as the O2 sensor isnt used on WOT or VTEC.
WRT to the fault itself id bet on something wiring related from the sensor wires back to the ECU... See if you can trace the wires under the car and spot any nicks or insulation degradation.
The sensor you have doenst have the life of a Bosch or NTK but they are still good, so if it is the sensor you may have got a duff one.
Shame we cant see the voltages the sesnor is giving out as that would give a good clue - need an AFR gauge or multimeter fo such a thing though...
WRT to the fault itself id bet on something wiring related from the sensor wires back to the ECU... See if you can trace the wires under the car and spot any nicks or insulation degradation.
The sensor you have doenst have the life of a Bosch or NTK but they are still good, so if it is the sensor you may have got a duff one.
Shame we cant see the voltages the sesnor is giving out as that would give a good clue - need an AFR gauge or multimeter fo such a thing though...
05-10-2007, 01:16 PM
#3
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I change mine the other day for a Toyota Denso one, car feels so smooth now. I think they can cause issues even without throwing a code.
Wiring does sound a possible issue. Unless you have ran some crappy supermarket fuel when there was the silicon contamination?
Wiring does sound a possible issue. Unless you have ran some crappy supermarket fuel when there was the silicon contamination?
05-10-2007, 01:17 PM
#4
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Originally Posted by Dark Blue Mark,May 10 2007, 08:36 PM
Hi Jamie, you will be ok on track as the O2 sensor isnt used on WOT or VTEC.
WRT to the fault itself id bet on something wiring related from the sensor wires back to the ECU... See if you can trace the wires under the car and spot any nicks or insulation degradation.
The sensor you have doenst have the life of a Bosch or NTK but they are still good, so if it is the sensor you may have got a duff one.
Shame we cant see the voltages the sesnor is giving out as that would give a good clue - need an AFR gauge or multimeter fo such a thing though...
WRT to the fault itself id bet on something wiring related from the sensor wires back to the ECU... See if you can trace the wires under the car and spot any nicks or insulation degradation.
The sensor you have doenst have the life of a Bosch or NTK but they are still good, so if it is the sensor you may have got a duff one.
Shame we cant see the voltages the sesnor is giving out as that would give a good clue - need an AFR gauge or multimeter fo such a thing though...
The usual failure mode is that they become sluggish
05-10-2007, 01:23 PM
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I'm going to have half tomorrow afternoon off and get the front end up and my head underneath to see if there is anything wrong with the wiring.
Not been anywhere a supermarket fuel pump since my O2 sensor died first time round. Not that is was related to that.
Cheers guys.
Not been anywhere a supermarket fuel pump since my O2 sensor died first time round. Not that is was related to that.
Cheers guys.
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05-12-2007, 12:33 AM
#9
If its thown up the error then its because the values it is provding to the ECU are a long way outside of it's normal operating range.
I'm with Mark, it could well be a simple wiring fault or dirty connection. Im not familiar with the connections and my car isn't here, but try unplugging it from the harness a few times.
As the last gentleman says, O2 sensors can degrade with age, or contamination.
Maybe this is a Tesco fuel problem just rearing it's head again. Traces would remain in the fuel and filter for a long time. You did change the fuel filter?
I'm with Mark, it could well be a simple wiring fault or dirty connection. Im not familiar with the connections and my car isn't here, but try unplugging it from the harness a few times.
As the last gentleman says, O2 sensors can degrade with age, or contamination.
Maybe this is a Tesco fuel problem just rearing it's head again. Traces would remain in the fuel and filter for a long time. You did change the fuel filter?
05-12-2007, 04:18 AM
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I had a look last night and took the O2 sensor off the car. I traced the wiring back to the bulkhead and couldn't see any damage to the harness under the car/in the engine bay.
I noticed that two of the plugs spade connectors where caked in a black powder. I spent some time cleaning all four pins up so they were nice and shiney, and I could see there was some kind of "gunk" into the connector as well. The two pins that were covered in this black powder went to the two white wires, which from memory are for the heated element in the sensor.
I put it all back together and had a better look underneath at other connectors and they all looked okay. I then went for a long drive to see if it felt any better. It was a bit hard to tell tbh, as I've become very used to how the car was behaving. Once the car had fully warmed up, I pulled over, pulled the fuse for the ECU. I then redlined it and really gave it some along the A4.
So far I've been out in the car a few times now, and done 30+ miles and the CEL has not returned. So far the cars not hesitated on me, but I'm still waiting for it to reappear.
m1bjr - I honestly don't think I got caught up in the fuel problems back in March, it was just by chance that my O2 sensor died, so I don't think I have any contamination.
I noticed that two of the plugs spade connectors where caked in a black powder. I spent some time cleaning all four pins up so they were nice and shiney, and I could see there was some kind of "gunk" into the connector as well. The two pins that were covered in this black powder went to the two white wires, which from memory are for the heated element in the sensor.
I put it all back together and had a better look underneath at other connectors and they all looked okay. I then went for a long drive to see if it felt any better. It was a bit hard to tell tbh, as I've become very used to how the car was behaving. Once the car had fully warmed up, I pulled over, pulled the fuse for the ECU. I then redlined it and really gave it some along the A4.
So far I've been out in the car a few times now, and done 30+ miles and the CEL has not returned. So far the cars not hesitated on me, but I'm still waiting for it to reappear.
m1bjr - I honestly don't think I got caught up in the fuel problems back in March, it was just by chance that my O2 sensor died, so I don't think I have any contamination.