I'm trying to fix my o2 sensor problem on my 98 Tacoma. it started a while back when the check engine light came on. the code was po125,po130 and po133. I checked the o2 sensor with meter and it checked out good. then I checked the wiring harness with meter and it showed it was getting 12 volts but it was not getting a ground. I though that I could tie a wire into the heater ground on sensor and ground it to the truck frame and the ground would be ok. that did not work and not I'm getting code po1135 saying ground fault. question is could the po125 be the main problem, I changed the thermostat and that did not help. Could it be the temp sensor? could someone steer me in the right direction? thank you
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Going Crazy With This Problem ~ O2 Sensor On 98 Tacoma
The 02 sensors have a built in heater in them. It does not mater how hot or cold the engine is. 125 is low coolant, so top off the rad. and pressure test for leaks. 130 and 133 is o2 sensor bank 1 sensor 1. The sensor in front of the cat. This is the sensor that controls fuel trim. The only problem with changing the sensor, is that the sensors all work together, so if you change 1 you need to change them all. Do you have 4 sensors or just 2. If you have 4, you could always swap the 2 front sensors and see if the codes change.
Its common for the heater in the o2 sensor to go out. As longas the wiring looks good (no smashed or burn spots) I would replace both sensors.
It depends, but about 60,or75 each about I think
The sensors run about $75 each for Bosch.
Check the maf sensor to, make sure its clean. If it needs cleaning use sensor safe electronics cleaner on it. But do not touch the sensor with anything but the sprayed cleaner. I had the same issue about 8 yrs ago on my 99 Tacoma, a friend of mine that's a mechanic told me after I replaced both sensors with no change that a dirty Maf sensor can sometimes set off the o2 sensors, cleaned the maf sensor and problem solved. Mac sensor cleaning is now part of my routine maint.
Check the maf sensor to, make sure its clean. If it needs cleaning use sensor safe electronics cleaner on it. But do not touch the sensor with anything but the sprayed cleaner. I had the same issue about 8 yrs ago on my 99 Tacoma, a friend of mine that's a mechanic told me after I replaced both sensors with no change that a dirty Maf sensor can sometimes set off the o2 sensors, cleaned the maf sensor and problem solved. Mac sensor cleaning is now part of my routine maint.
Traverse City Bob
Member
What is the Maf Sensor on a 99' Tachoma and where is it?
Traverse City Bob
Member
What is a Maf Sensor and where is it on a 99' Tacoma???
A mass (air) flow sensor (MAF) is used to find out the mass flow rate of air entering a fuel-injected internal combustion engine. The air mass information is necessary for the engine control unit (ECU) to balance and deliver the correct fuel mass to the engine.
Check out this video for the Mass Air Flow Sensor 1995 - 2004 Tacoma
Check out this video for the Mass Air Flow Sensor 1995 - 2004 Tacoma
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Traverse City Bob
Member
Thanks for your prompt response...and the great Video....I think I can handle that.
Should be very easy and important maintenance thing.
Easy fix replace sensors and find a 02 deleting kit no more problem did this on my 05 tacoma cause I got rid of 2 cats with long tube headers
Any updates on this issue?
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