Horrible Gas Mileage, How Much to Replace...

[OBBass]

I'd like to know how he figures the cat is bad.

Replace the o2's and be done underneath, I say.

As for those gauge tire cap thingies, save your money. They leak, they're inaccurate, they suck balls. Use that money and get yourself a nice gauge, not one of those pen ones, they suck. Get a fancy dial gauge, nothing more than fifteen bucks or so, but the 4-dollar ones are very finicky and don't like being abused. Use that instead.

starting to rattle a bit, he didn't say it was bad, but he said it was starting to wear out, he showed me a few insides of some other ones too, I think I will try with the o2 sensors myself, wish I had a lift though, what brand should I go with?

Bosch is top notch, I had to replace all 4 on my car, cost about $200 dollars. took me from 18 to 20 mpg, now I'm down to around 13 because of some tranny problems, and a faulty ignition coil.

[dereileak]

I'd like to know how he figures the cat is bad.

Replace the o2's and be done underneath, I say.

As for those gauge tire cap thingies, save your money. They leak, they're inaccurate, they suck balls. Use that money and get yourself a nice gauge, not one of those pen ones, they suck. Get a fancy dial gauge, nothing more than fifteen bucks or so, but the 4-dollar ones are very finicky and don't like being abused. Use that instead.

starting to rattle a bit, he didn't say it was bad, but he said it was starting to wear out, he showed me a few insides of some other ones too, I think I will try with the o2 sensors myself, wish I had a lift though, what brand should I go with?

Bosch is top notch, I had to replace all 4 on my car, cost about $200 dollars. took me from 18 to 20 mpg, now I'm down to around 13 because of some tranny problems, and a faulty ignition coil.

Bosch makes awesome stuff, but I heard they have had problems with o2 sensors, mainly if you replace your oem one thats not bosch with a bosch, but if it was factory bosch then you should be good, mine were ntk/ngk, so I replaced them with those, so far so good, I just got my rear one today, looks awesome, shouldnt take long at all to replace since the bank 2 one is right in the open by the exhaust

[dereileak]

UPDATE/HELP

Ok, so I was good for about 3 days then it was right back to normal, and for all I know those 3 days were just the placebo effect. I replaced it with the same brand that was in there for oem and I am still getting the code p0135, I also got the code p0134 for like a day afterwords too. I dont know what to do, I dont want to pay all this money to have a dealership hook there big machine up to it, but I am kinda stuck, and input would be good. Its really hard to get to the harnesses for this thing so I am not sure. My scan tool showed a solid .3v's from both sensors when reading them, but that could be a scan tool error, I believe that is the reference voltage that the pcm sends to it to then have it adjust the resistence, then causing the voltage to change.

Vehicle - 1999 Dodge Grand Caravan SE 3.3 Flex

New Part- Amazon Part <--- Link (Same brand as the one that I took out)

Codes- P0135, also had P0134 for one day

Any help would be so awesome as I am eating gas so crazily fast its sad, 9mpg

[JaM Customs aka mprete]

http://forums.focaljet.com/problems-service-recalls/607823-how-fix-p0135-engine-code.html read the first post, that might help. never heard that before but something easy to check.

trouble code P0135 - Oxygen O2 Sensor Heater Circuit Malfunction (Bank1, Sensor1)

trouble code P0134 - Oxygen 02 Sensor Circuit No Activity Detected (Bank 1 Sensor 1)

do you have an o-scope? that would be the best tool for you. if you do figure out what the freq or the o2 sensor is, probe at the sensor. start the car and look at the pattern. take the time on the screen and divide it by how many cycles are on the screen and thats your freq. should be from .5-5 hz if its above 5 hz then thats an indication of a misfire. if you get no signal then you have a bad o2. if you can do that let me know what you get.

[JaM Customs aka mprete]

P0134

oxygen sensor in this test and is mounted on the exhaust manifold. Upstream oxygen sensor operation is monitored when engine is running for more than 2 minutes and engine coolant temperature is greater than 170°F (76.7°C). DTC may be stored in Powertrain Control Module (PCM) if upstream oxygen sensor signal voltage is .35-.55 volt for 1.5 minutes. Possible causes are: defective upstream oxygen sensor, defective PCM, or defective connectors or wiring.

P0135

Upstream oxygen sensor is referred to as 1/1 O2 sensor in this test and is mounted on the exhaust manifold. Upstream oxygen sensor heater operation is monitored after ignition is turned off and engine cools down. DTC may be stored in Powertrain Control Module (PCM) if no upstream oxygen sensor signal is received when the PCM powers up and oxygen sensor heater. Possible causes are: defective upstream oxygen sensor or heater, defective Auto Shutdown (ASD) relay circuit, or defective connectors or wiring.

i have testing procedures for both codes but you need a scan tool and an DVOM or an o-scope and maybe a couple other specialty tools but this should help you out for now

[dereileak]

http://forums.focalj...ngine-code.html read the first post, that might help. never heard that before but something easy to check.

trouble code P0135 - Oxygen O2 Sensor Heater Circuit Malfunction (Bank1, Sensor1)

trouble code P0134 - Oxygen 02 Sensor Circuit No Activity Detected (Bank 1 Sensor 1)

do you have an o-scope? that would be the best tool for you. if you do figure out what the freq or the o2 sensor is, probe at the sensor. start the car and look at the pattern. take the time on the screen and divide it by how many cycles are on the screen and thats your freq. should be from .5-5 hz if its above 5 hz then thats an indication of a misfire. if you get no signal then you have a bad o2. if you can do that let me know what you get.

I dont have an oscope unfortunatly, the sucky thing about this sensor is where it is at, to get to it you have to jack the van up, and go from underneath, you follow your arm up the cat convertor about 3-4 feet then to reach it, I had to replace it almost all through touch instead of seeing it, let me say it was a bitch, so i dont think I will be able to test it with a dmm cause of its location, I may be able to get the wiper assembly removed and then get to it, but that is my only chance, I see it as this though, if both sensors give the same code, then there must be a fault somewhere else, hopefully not the wiring, but it could very well be

I checked fuses for my van, and I didn't see any related to my o2 sensor, any clue what name it would be under? I should try cleaning the contacts of them, but I don't know what fuse it is under

[JaM Customs aka mprete]

if you notice in the first of those 2 posts that both codes are for the same sensor. the upstream sensor. sensor 1 bank 1. thats the sensor before the cat. the other sensor has NO codes.

and about the fuse to be honest no i dont because the wiring should go straight to the pcm but maybe some cars have one. yours just may not have one. but you said you have a scan tool... can you see the short term and long term fuel trim? (STFT and LTFT)

[dereileak]

if you notice in the first of those 2 posts that both codes are for the same sensor. the upstream sensor. sensor 1 bank 1. thats the sensor before the cat. the other sensor has NO codes.

and about the fuse to be honest no i dont because the wiring should go straight to the pcm but maybe some cars have one. yours just may not have one. but you said you have a scan tool... can you see the short term and long term fuel trim? (STFT and LTFT)

I will run out there quick and see if I can get some numbers on that, one sec

[dereileak]

alright, I cant get any fuel trim info, its supported by the app, just not for my vehicle yet, but it shows a constant .3v on both o2 sensors, and so far with this app if it shows data it is right, otherwise it wont show anything, it also says for fuel status that when I start its open loop, normal cause it has to heat up the sensors, but then it goes to sys-fail after about 1 minute. I think there must be something with a fuse causing the heater curcuits to not be able to heat up, that would cause that code and those voltages I would imagine, or some bad wiring, I can test the second o2 sensor, as it is easy to reach, and see if its pushing out the right voltages, this really sucks though, cause I am eating gas really bad, I started running e85 today, figured if it eats gas, why not have it be cheaper, by vehicle is all setup to run that stuff, also it is fucking cold out right now, ha ha

[JaM Customs aka mprete]

yea to get stft and ltft you need to have run the car till it goes into closed loop operation. if that sensor is easy to get to then check the voltage at the sensor because .3v is to low. check the ground at the pcm also. and there should be a freeze frame data on when you look at the scan tool. look at the data and if you can record what some of that stuff is.