O2 sensor error related to blinking O/D?
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Senior User
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From: New Mexico
O2 sensor error related to blinking O/D?
I've been trying to troubleshoot my O2 sensors(three are bad). My O/d light started blinking once a few weeks ago (shifting was normal). After I restarted the truck it stopped.
Today I replaced one of the bad O2 sensors and went on a testdrive to try to get the CEL on so I could figure out if the O2 sensor was the problem. While getting on it the O/D light started blinking again (No CEL). I pulled the codes and all I got were P0141P P0161P which I expected. I erased them and the O/d light stopped blinking.
Any input?
Today I replaced one of the bad O2 sensors and went on a testdrive to try to get the CEL on so I could figure out if the O2 sensor was the problem. While getting on it the O/D light started blinking again (No CEL). I pulled the codes and all I got were P0141P P0161P which I expected. I erased them and the O/d light stopped blinking.
Any input?
Hotshot
Joined: Jan 2004
Posts: 19,762
Likes: 1,079
From: St Louis
Originally Posted by StephenH
I have a cheap one but it is supposed to read ford codes.
It is unlikely that you actually have that many bad O2 sensors. Don't waste your money on them.
With your set of symptoms, I'd suspect an intermittent short circuit on the rear O2 heater circuit or that the harness has an intermittent open that is opening up when the vehicle accelerates. This exact same circuit also powers the electrical components in the transmission so a fault in the circuit will affect both subsystems.
First, inspect the O2 sensor harnesses to see if any are laying on either an exhaust or a moving drivetrain component. If found, repair as needed.
Steve
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From: New Mexico
Thanks for your help. I'm pretty sure the o2 sensors are bad though. I checked all of the wiring and then replaced sensor 1 bank 1 and I havent gotten P0135 again. 141 and 161 still keep turning on the CEL>
The truck is still sucking down way to much gas. As soon as I can afford it, I will replace the other two.
Havent seen the o/d light back on since my tranny flush yesterday. So we will see...
The truck is still sucking down way to much gas. As soon as I can afford it, I will replace the other two.
Havent seen the o/d light back on since my tranny flush yesterday. So we will see...
Cargo Master
Joined: Dec 2003
Posts: 2,182
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From: Saint Augustine, FL
Cheap scanners only read OBDII codes. They do not read manufacturer specific codes. So you won't be able to read the transmission codes with your cheap scanner.
If all of your O2 sensors went bad then I suspect something contaminated them.
Steve
'95 Clubwagon XLT
If all of your O2 sensors went bad then I suspect something contaminated them.
Steve
'95 Clubwagon XLT
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Senior User
Joined: Dec 2006
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From: New Mexico
Originally Posted by Clubwagon
Cheap scanners only read OBDII codes. They do not read manufacturer specific codes. So you won't be able to read the transmission codes with your cheap scanner.
If all of your O2 sensors went bad then I suspect something contaminated them.
Steve
'95 Clubwagon XLT
If all of your O2 sensors went bad then I suspect something contaminated them.
Steve
'95 Clubwagon XLT
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Hotshot
Joined: Jan 2004
Posts: 19,762
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From: St Louis
The two downstream sensor fault codes have to do with the heater circuit only, nothing to do with the sensor element itself. Silicone or any other contaminant cannot cause these fault codes.
If you do decide to replace your downstream sensors, you'll likely just be wasting your money since I already described the most likely scenario. Since the indicated fault code for the upstream sensor you already replaced was also a heater error, you likely wasted the money on that sensor also.
Fault codes are not a pinpoint diagnostic. They don not definitively declare that any given part is defective and should be replaced. They are a data point in a diagnostic procedure that, if followed correctly, should yield a proper and accurate diagnosis and repair.
Proceed at your own risk.
If you wish, you can do a manual test of the sensors' heater elements with a simple multimeter to check for short-to-case, short-to-sensor element, and heater continuity faults.
The downstream sensors have absolutely nothing to do with your fuel consumption. They are there solely for the purpose of monitoring catalytic converteer performance.
Steve
If you do decide to replace your downstream sensors, you'll likely just be wasting your money since I already described the most likely scenario. Since the indicated fault code for the upstream sensor you already replaced was also a heater error, you likely wasted the money on that sensor also.
Fault codes are not a pinpoint diagnostic. They don not definitively declare that any given part is defective and should be replaced. They are a data point in a diagnostic procedure that, if followed correctly, should yield a proper and accurate diagnosis and repair.
Proceed at your own risk.
If you wish, you can do a manual test of the sensors' heater elements with a simple multimeter to check for short-to-case, short-to-sensor element, and heater continuity faults.
The downstream sensors have absolutely nothing to do with your fuel consumption. They are there solely for the purpose of monitoring catalytic converteer performance.
Steve
Last edited by projectSHO89; Dec 21, 2006 at 09:14 AM.
Guest
Joined: Nov 2004
Posts: 7,988
Likes: 55
From: north west new jersey
the guys are correct the chaep scaners only read engine faults. not the trans, abs. or air bag faults.
steve
you bring up a very big and true thing many home techs and even some shop techs fail to do. find the true cause before selling or buying unreturnable parts . to many times i have found a wire harness fall and burn on the exhaust or rub though by a moveing part that caused the problem.
we all need to understand that we need good tools to work on todays vehicles. a 60 dollar scaner will not help as much as some one haveing a scanner of 1k or better in cost that dose read all the codes " engine.trans, abs, air bag" that can cause the problem plus help read the part as it works on the running vehicle while road testing or working on it.
a bad shifting trans can be that way because the engine has a problem and the other way around with the engine. even a bad vacume hose can cause problems that i have seen mechaincs go crazy over.
www.obd-codes.com is a web site with a very big listing of codes and how to help for many brands and it keeps getting bigger every day
steve
you bring up a very big and true thing many home techs and even some shop techs fail to do. find the true cause before selling or buying unreturnable parts . to many times i have found a wire harness fall and burn on the exhaust or rub though by a moveing part that caused the problem.
we all need to understand that we need good tools to work on todays vehicles. a 60 dollar scaner will not help as much as some one haveing a scanner of 1k or better in cost that dose read all the codes " engine.trans, abs, air bag" that can cause the problem plus help read the part as it works on the running vehicle while road testing or working on it.
a bad shifting trans can be that way because the engine has a problem and the other way around with the engine. even a bad vacume hose can cause problems that i have seen mechaincs go crazy over.
www.obd-codes.com is a web site with a very big listing of codes and how to help for many brands and it keeps getting bigger every day
Thread Starter
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Senior User
Joined: Dec 2006
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From: New Mexico
Originally Posted by projectSHO89
The two downstream sensor fault codes have to do with the heater circuit only, nothing to do with the sensor element itself. Silicone or any other contaminant cannot cause these fault codes.
If you do decide to replace your downstream sensors, you'll likely just be wasting your money since I already described the most likely scenario. Since the indicated fault code for the upstream sensor you already replaced was also a heater error, you likely wasted the money on that sensor also.
Fault codes are not a pinpoint diagnostic. They don not definitively declare that any given part is defective and should be replaced. They are a data point in a diagnostic procedure that, if followed correctly, should yield a proper and accurate diagnosis and repair.
Proceed at your own risk.
If you wish, you can do a manual test of the sensors' heater elements with a simple multimeter to check for short-to-case, short-to-sensor element, and heater continuity faults.
The downstream sensors have absolutely nothing to do with your fuel consumption. They are there solely for the purpose of monitoring catalytic converteer performance.
Steve
If you do decide to replace your downstream sensors, you'll likely just be wasting your money since I already described the most likely scenario. Since the indicated fault code for the upstream sensor you already replaced was also a heater error, you likely wasted the money on that sensor also.
Fault codes are not a pinpoint diagnostic. They don not definitively declare that any given part is defective and should be replaced. They are a data point in a diagnostic procedure that, if followed correctly, should yield a proper and accurate diagnosis and repair.
Proceed at your own risk.
If you wish, you can do a manual test of the sensors' heater elements with a simple multimeter to check for short-to-case, short-to-sensor element, and heater continuity faults.
The downstream sensors have absolutely nothing to do with your fuel consumption. They are there solely for the purpose of monitoring catalytic converteer performance.
Steve
I'm not sure I understand what you are saying. I replaced the sensor that was causing P0135 and I havent got that code again (passenger side before cat). How is that a waste of money?
The wiring looks ok to me. I would think that a wiring short would have caused all four sensors to throw a code rather than just the three that did.
The old downstream sensor for that side seems to be working fine as it hasnt set any codes, so I will not replace it
The two on the driver's side are still not working so I assume that they are bad too. As soon as I can afford $50 i will replace the upstream one (mpg issue) and then the downstream later on.
I dont know the history of the truck, so I have no idea if they all went bad at once or over time. The CEL being on helped me buy the truck a lot cheaper than normal.
Guest
Joined: Nov 2004
Posts: 7,988
Likes: 55
From: north west new jersey
stephen
as one who was both dealer and factory feild machanic i have seen 3 and even 4 o2 sensers fail .but even more so you most be very sure they have. before you go spending money on them.
with the aid of lap tops and some very good programs and tools.i now use my laptop as my main diag. tool. you may find these to more of a aid then a cheap scaner to help you prpoerly repair you ride.
good luck
as one who was both dealer and factory feild machanic i have seen 3 and even 4 o2 sensers fail .but even more so you most be very sure they have. before you go spending money on them.
with the aid of lap tops and some very good programs and tools.i now use my laptop as my main diag. tool. you may find these to more of a aid then a cheap scaner to help you prpoerly repair you ride.
good luck
Hotshot
Joined: Jan 2004
Posts: 19,762
Likes: 1,079
From: St Louis
All of your fault codes reported have been heater circuit codes. The heaters are used only during cold engine startup then are not used after the engine enters closed-loop operation.
The only thing in common between all of your original faults is the power circuit that feeds the O2 sensor heaters and the transmission solenoid circuits.
Check the heaters with a meter before buying new sensors.
I still suspect you have an intermittent wiring harness issue. Testing theindividual sensors will either confirm that they are, if fact, good or whether they are faulty.
Steve
The only thing in common between all of your original faults is the power circuit that feeds the O2 sensor heaters and the transmission solenoid circuits.
Check the heaters with a meter before buying new sensors.
I still suspect you have an intermittent wiring harness issue. Testing theindividual sensors will either confirm that they are, if fact, good or whether they are faulty.
Steve