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Could use some help/advice on diagnosing an E046 trouble code for a '92 Eldorado with the 4.9 liter engine. I also failed my last smog check because of excessive NOx, btw. I'm thinking the two things are related. E046 is the the 'Left to Right Bank Fueling Difference' that will produce a Service Engine Soon light. My E046 is the single current code but the SES only comes on intermittently. My due diligence of Googling other people's experience with the E046 on this and other forums has been a bit disappointing. Many of the E046 complainers don't seem to use a Factory Service Manual for diagnosis, and most of the E046 threads I've seen have the guys replacing O2 sensors and fuel injection parts without really taking a more scientific approach (i.e. not throwing parts at the problem and hoping it will go away). Apparently the O2 sensors can be bad and produce an E046 without spitting out a more O2-specific trouble code. Anyway, the fault tree for E046 can be found on my attachment IMG_0379.jpg with some more info on E046 found in attachment IMG_0385.jpg Going through the steps of the tree, I am witnessing the ED35 (Right O2 sensor cross count) bouncing around from 0 to a high of 34, while the ED34 (Left O2 sensor cross count) varying between 0 to a high of about 24. These values do not seem to linearly increase as the car accelerates or travels at a higher rate of speed. Even just idling in Park in my driveway can produce non-zero cross counts. What should I do now? I have seen previous posts with differing opinions, e.g. the actual numerical value doesn't matter, it's the frequency of the numbers changing, the 0 value is no good, a high number is better, etc. and so forth. Some previous posters don't seem to have a really good grasp of what 'cross count' really means (me included). I'm taking an educated guess that if the cross count reading is '5' as an example, this means the O2 sensor is dictating 5 changes per second from a rich to a lean burn. Is that correct? So I have many more questions than answers, is there somebody out there that can help me with this dilemma? I feel that just blindly replacing O2 sensors as historically been done might be my last resort otherwise. Thanks, cadillac fellas.
i think i may have a bad O2 sensor however the problem is my Cadillac is a 1996 and the test computers to run codes only go back to 97' any ideas? also is there a common O2 sensor that goes bad or is it just random Thanks!
There are oxygen sensors that control the fuel delivery and there are those that check catalytic converter function. I sometimes get the engine light turn on when it is cold, with codes that tell me that the heating is not working properly in the O2 sensors (PCM 0135 and 0155). Those codes are for the O2 sensors in the manifolds (one for each cylinder bank). I am now about to replace those two O2 sensors, and I have two questions: What is the difference between AFS109 and AFS125? Both have the following (identical) description on Rockauto: SENSOR,HTD OXY(POSN 1) IN EXH MANIFOLD/CROSSOVER. They have different prices. Is there any reason to replace the other two O2 sensors (one on each side of the catalytic converter)? Even if they were a bit "tired", that should still not effect engine performance in any way, correct? Only the two in the manifolds are involved in the closed-loop engine control, right?
As some of you know, I am about to change my O2 sensors (the two in the manifolds), since I occasionally get codes telling me that the heating is not working properly (PCM 0135 and 0155). I just checked some readings with my OBD link computer interface and read the following values: O2 Response Lean/Rich Transitions Time Bank 1 Sensor 1: 25 ms. O2 Response Lean/Rich Transitions Time Bank 2 Sensor 1: 83 ms. O2 Response Rich/Lean Transitions Time Bank 2 Sensor 1: 94 ms. I also meant to record the B1S1 R/L Transitions, but accidentally recorded the following isntead: O2 Response Rich/Lean Switches Bank 1 Sensor 1: 145. Does anyone know what that number means? If it means switches per second, then one switch would be less than 7 ms. Anyways, comparing Lean/Rich for B1S1 and B2S1 above it is clear that the Bank 2 sensor is slower than it could be. I also got the following reading, which I suppose are for the O2 sensor in front of the cat. conv. O2 Response Lean/Rich Transitions Time Bank 1 Sensor 2: 30 ms. O2 Response Rich/Lean Transitions Time Bank 1 Sensor 2: 44 ms. I do not worry very much about the last to values, since as far as I know that sensor is only involved in monitoring the efficiency of the catalytic converter. Since it is hence not involved in the feedback loop for engine control, its response time should not matter (other than probably setting a code if it got very slow). Is that correct? Is the O2 sensor just in front of the cat involved in the engine control in any way? Does anyone know what the normal switch times are for new O2 sensors? I will change the two sensors in the manifold/crossover either way, so I will find the answer to the last question, but I am unsure if there is any point in replacing the "third" sensor in front of the catalytic converter. /Jonas