P0132 - Oxygen Sensor Circuit High Voltage (Bank 1 Sensor 1)
Hi guys. Excuse me for butting in, but I have some laptop battery that needs to be used up, so here I am. Wrenchtech is right, but you made some other comments that got my attention. The dash board has nothing to do with this problem, so you shouldn't even be discussing that or worrying about it.
The oxygen sensors usually don't cause this problem, and it's highly unlikely you'd have two in a row doing this. The most common cause is a wiring harness that fell down onto hot exhaust parts and two wires melted together. I should point out too, as you already know, that fault codes never say to replace parts or that they're bad. They only indicate the circuit or system that needs to be diagnosed, or the unacceptable operating condition. When a part is referenced in a fault code, it is actually the cause of that code perhaps half of the time. First you have to look for cut or grounded wires, stretched or corroded connector terminals, corrosion between terminals, and things like that.
Your main concern is mechanical damage to the engine, and in a roundabout way a problem could develop. We ran engines for decades without oxygen sensors, but there wasn't much that could cause trouble with a carburetor. With all the computer controls today, it would be almost impossible to know where to start a diagnosis if a computer didn't detect the problem and set a diagnostic fault code to get us started. Every computer runs a batch of tests constantly as we drive and other tests at various times. Many of those tests pass or fail based on comparing a sensor reading to some other sensor reading or operating condition. For example, the Engine Computer knows that when the engine has been off for at least six hours, the coolant temperature sensor had better be reading the same temperature as the intake air temperature sensor or any other temperature sensor.
The base fuel metering calculations are based on a number of things like intake air temperature, throttle movement, engine load and speed. Upstream oxygen sensor readings come in later when the computer wants to see the results of its calculations, then it makes fine tuning adjustments. Where the problem can come up is when a fault code is set for one sensor, some of the self tests that rely on its readings for comparison might be suspended. This gets into an area I'm really not qualified to offer advice on other than to share what I've been taught. If you look in some of the diagnostic manuals that address a specific fault code, there will be a long list of the conditions that must be met for that code to set. Along with the "problems" or symptoms, one of those conditions is always that certain other fault codes can't already be set. Some of those codes prevent some self tests from running only while the problem is acting up, and some codes stop tests from running even if the problem is intermittent and not acting up right now.
What that means for you is any test that needs readings from the oxygen sensor can't be run because thanks to that code 132, the computer knows it can't trust the results. A test will be suspended. Two things can happen. One is a relatively minor problem that you don't know about could become serious if ignored. A spark-related misfire, for example, could allow unburned fuel to go into the exhaust system where it will burn in the catalytic converter and overheat and damage it. The computer would see the absence of lean exhaust pulses about twice per second and set a fault code for "running too rich too long". It should still set a misfire code, but that one has its own set of conditions that must be met first.
The second place where an ignored code becomes an issue is a second problem may have developed and it didn't get detected because of a suspended test. Where I'm more familiar with this is with anti-lock brakes. If a wheel speed sensor has a problem and you get it repaired right away, if a second sensor fails two weeks later, that too will be detected. The problem is when people wait to have the first problem repaired. With the first fault code in memory, some tests for the other sensors are suspended. If that second sensor fails two weeks later, the mechanic will have no way of knowing about it. He only has the one fault code to go on when providing an estimate for what it will cost to do the diagnosis. Once he repairs the cause of the fault code, (replace the sensor or fix the wiring), and goes for a test drive, the self tests resume, and that's when the second sensor problem is detected. The warning light comes right back on and the customer incorrectly assumes the problem wasn't diagnosed or repaired properly. This is frustrating to mechanics and car owners.
The same thing can happen with engine controls but Wrenchtech can explain that better. As Paul Harvey used to say, "I'm going to tell you more than I know". If I understand correctly, at certain times the Engine Computer will turn on the purge solenoid to allow fumes to be drawn out of the charcoal canister and be burned in the engine. At that time it expects to see a more rich condition being reported by the oxygen sensor because more fuel is being dumped in. I seem to recall a fault code will be set if it doesn't see that expected change in mixture. This would be a case of where it can't make that judgement if it can't trust the oxygen sensor readings.
Where I would start is with a visual inspection of the wiring harness where it goes over the exhaust manifold. Next would be to connect a scanner to view live data and see what voltage is shown for that sensor. If it appears to be normal, as in less than one volt, that would say you're looking for an intermittent problem that isn't acting up right now. Record the code, erase, it, then drive the car to see how it performs. Pay attention to what is happening when the problem returns. Pot holes, accelerating, turning, shifting to reverse, ... Those types of things can provide clues for where to look. If the code sets again right away before you even start driving, that's a sign of a hard failure that is always there. Those are much easier to find.
I didn't follow what you were saying about removing the sensor from the exhaust manifold. If two wires are shorted together inside it, all you have to do is unplug it. It shouldn't be necessary to remove it. There will be a 12 volt feed wire going to it for the heater that gets it up to operating temperature faster than the exhaust alone can do. That 12 volt circuit also feeds the ignition coil, injectors, alternator field, and fuel pump or pump relay. I could see where shorting two melted wires together could draw that 12 volts down low enough to disable that circuit, but there's a fuse in there too. That could also put that 12 volts onto the signal wire and cause this code. That wouldn't be a direct short to ground, but it could still affect the coil and injectors enough to cause a running problem.
Thursday, June 23rd, 2016 AT 12:16 AM
