code 136

[94redranger]

136 (R) Oxygen sensor not switching/system lean Left or Front HO2S - Fuel control

I get this code when the engine is running. I know I have a small exhaust leak where the exhaust port meets the manifold, however my truck shouldn't run rough until the O2 sensor warms up. The computer doesn't go into closed loop until the coolant temperature sensor tells the PCM the engine is warm. I believe they are heated as there are four wires going to them. Unless the warm up period is very short. I cleaned the MAF very well, TPS seems to be functional unless something else is wrong inside, and no vacuum leaks. Plugs, wires, all good. Possibly fuel pressure test I'll just have to get a testing kit. However this code seems so appropriate to my situation as there is an exhaust leak on left bank which would cause a false lean condition. Any help please.

 

[90rangersuper]

i believe the o2 is heated all the time, i had my truck off for 3 days did some work on it without starting it, felt the O2 and it was warm, it was only about 45 here, by the code it would be the front O2, the exhaust leak would only let air in our out before the cat the rear one would still adjust the reading to get it to run right, i would replace the O2, got mine at advance about 70 bucks

 

[Yellowsplash]

Fix the leak before doing anything else...It will cause false readings.
You also have to remember that the ecu uses the o2 sensor to adjust high and low fuel trims.

 

[94redranger]

i believe the o2 is heated all the time, i had my truck off for 3 days did some work on it without starting it, felt the O2 and it was warm, it was only about 45 here, by the code it would be the front O2, the exhaust leak would only let air in our out before the cat the rear one would still adjust the reading to get it to run right, i would replace the O2, got mine at advance about 70 bucks

So what you are saying is the O2 sensors are always providing information to the PCM even at start up?

 

[90rangersuper]

with the o2 being heated when you start up, the computer knows its a cold start because of the other sensors, the coolent temp sensor would show cold, the o2 just measures the contents of the exhaust gas so you dont end up burning to much or to little gas, when my o2 went out it was running pig rich, your rear o2 would measure weather the cat it taking out the approate chemicals , you need to get that leak fixed before your cat so the o2 can do a proper job of adjusting the fuel mix

 

[94redranger]

so are you saying that the o2 sensors are functioning and helping the computer adjust the fuel/air mixture right off a cold start?

 

[fastpakr]

No - my guess would be that they've simply caused the fuel trim to be off, causing your cold start issues.

Fix your exhaust issue FIRST. No further diagnosis can be done on this issue with that unresolved.

 

[94redranger]

So I fixed the exhaust leak finally and still have the same pinging whether cold or warm. I was doing some research on O2 sensors and read that if oil, antifreeze etc. coats the outside of the sensor that will kill it. Will it actually wreck the sensor or can it be cleaned off and make the sensor good again. It says it can't have any oil or crap on the outside because it needs to measure how much oxygen is in the atmosphere. I don't know what part of the sensor measures that. Anyways I did clean all the oil off my right O2 sensor, even though the code is about the left one so I cleaned the outside of the left one too.
Now I want to test them with my volt meter and I need to know which is the output wire. There are four wires at the sensor, two white, black and a gray. I do leave the wires connected to the PCM right? As long they show that they are switching from .1-.9 volts than they are good right?

 

[fastpakr]

I'll try to look up that info tomorrow. Before you go through all this, though - reset the PCM, drive for a little while (15-20 minutes is plenty), then run the KOEO, Continuous, and KOER tests again and report the results. I can look up the pinpoint tests for whatever you come up with.

 

[94redranger]

Ok thank you I'll get that done ASAP.

 

[94redranger]

Ok so I reset the PCM, drove around for 20 minutes and I didn't get any KOEO or continuous codes, but I did get these KOER codes:

172 (R,M) Oxygen sensor not switching - system is or was lean - Single, Right or Rear HO2S - Fuel control
136 (R) Oxygen sensor not switching/system lean Left or Front HO2S - Fuel control
411 (R) Idle speed system not controlling idle properly (generally idle too high) - ISC

 

[94redranger]

Does anyone know if I can unplug the O2 sensors to see if it makes a difference or will that just make it worse. As well Does anyone what colour wire the output wire is I have two white, a black and a gray. Will having one O2 sensor coated with oil on the outside wreck it, I read that they tell how much oxygen is in the atmosphere by something on the outside.

 

[Power Ranger 1]

Damn it seems that all the same codes you have i do too and i have replaced every sensor and still have the same codes , i seen on here where the intake could be leaking so i pulled mine apart and found that one injector HAT was missing so i am trying to find one of them so i can put it back together to see if the intake was the problem feel you guys in later on progress

 

[Power Ranger 1]

Ok so i replaced the intake and the injector and still has the sputtering at around 2000 but if you go to wot it cleans up and runs great can anyone help me out before i blow this thing up

 

[94redranger]

So does anyone what colour the O2 output wire is? By the way my left O2 sensor is a little skinnier than the right, they are both before the cat, and when I order them it says it can be used left or right. Perhaps the previous owner replaced one and it was just a different size. Is Bosch OEM sensor supplier for '94 ford?