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Discussion Starter #1
Might as well get all the problems up for discussion and off my back. !

Been in the process of replacing alot of O2 sensors in the car lately. I always get the same CEL #P-0135 which indicates a defect in the heater of the O2 sensor.

I used 2 NLT O2 sensors when I first made the repair. The first one lasted about a month the 2nd failed at about 10 days. The "door knob" at the local parts desk suggested it was a lousy brand (DAH!! it's the Chrysler OEM brand isn't that funny?)
so I went premium with a Bosch Premium.
That Bosch last 2 weeks.

I'm now trying a Denso. No, it's not the good Denso stuff that's made in Japan, (like I use on my Toyota Rocket car). Nope, this cheap Chinese junk is assembled by expensive American labor here in the States.
 

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Have you checked any of the bad sensors to see if the heater coil is actually burned out? If I had to speculate, I'd say there is probably a bad connection or intermittant ground throwing these codes (and possibly putting it in open loop).
 

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Five sensors in that time frame says that it's the car, not the sensors. Absolutely the car. How did you determine that they are bad - just from fault codes? Either the harness/plug connection is faulty, or the car is 'poisoning' sensors, such as with antifreeze from a bad head gasket, which you should notice. So I'll go with wiring.
 

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After number three I would have started looking at the cause, not the result. Antifreeze, additives to the fuel, and as noted, wiring. Something ain't right, and I don't think it is five O2 sensors.
 

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He is getting code P0135 which is the 12 volt heater line in the 02 sensor. I suspect it is a wiring problem and perhaps the wiring harness got chaffed or contacted the exhaust manifold, melting the insulation and shorting out the 12 volt wire.

I hope all the old sensors were saved because they may not be bad at all.

How does the vehicle operate when you get this code? Is there any significant change in how it runs?... or are you just getting the MIL coming on.
 

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Compare the O2 sensor heater resistance readings at room temperature. Different brands may show different resistances and this may cause the PCM to throw the P0135 fault code.
Stick with OEM. I have had issues with Bosch in the past. Mopar or NGK/Denso should meet the factory specs.
The DG/Or wire is the 12 volt heater supply in from the ASD relay and the Or/Rd wire returns to the PCM for O2 heater control. The circuit isn't that complicated and obviously one of the components involved is failing.

P0135-1/1 O2 SENSOR HEATER FAILURE
When Monitored: The O2 Heater Monitor runs during O2 sensor cool-down period, after
a hot drive cycle, when engine is shut down with the ignition key turned OFF.
Set Condition: Using O2 sensor signal voltage readings, during O2 sensor cool-down
period, with heater OFF compared to O2 sensor signal voltage with heater ON.

POSSIBLE CAUSES
OPEN ASD RELAY OUTPUT CIRCUIT
O2S HEATER CONTROL CIRCUIT OPEN
O2S HEATER CONTROL CIRCUIT SHORTED TO GROUND
WIRING HARNESS INTERMITTENT PROBLEM
O2 SENSOR
PCM
 

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Discussion Starter #7
Wow--Thanks for all the response guys, I really do appreciate the view from outside these trees.

Mr Woods-Sad to say I don’t know which wire is the heater, what the OEM specification should be sought if I can perform a multimeter check? In that the new sensors perform perfectly for weeks at a time I would think to rule out connector or ground faults (?) Question.
CEL light comes on and no performance is affected. NO engine/exhaust smell. There is no wiring/insulation issue back up into the harness.

Mr Lincoln-from 47 years experience with cars I don’t perceive an anti-freeze leak or any smell of deposits on the “bad” sensors, even, before they fail.

Dana- I don’t use fuel additives. 

Crown-I agree, so I started with 2 NLK’s? which I was told, were OEM, one failed a 2 weeks the other at 5 weeks. The Bosch Premium lasted for 2 weeks. This Denso lasted 3 weeks.
I’m still re-reading your P-0135 1/1 info-it’s hard, for me, I never went to OBD school. 
-------------------------------------------
It seems the Forum moderator did not like my choice of words originally so I’ll try to make my hunch socially acceptable:

NLK –made and assembled in China (12 years ago too???)
Bosch-made and assembled in China ( I hoped for German )
Denso (Japanese brand)-made with Chinese parts
Anyone else see a pattern here??

On my “new” quest for an American part with American made parts assembled by Americans not one single supplier I’ve contacted (4) can tell me if Delphi, AC Delco, Ultrapower, Wells or Standard Motor Products uses American parts (??). I find this very disturbing and sense that the extent of out-sourcing of parts is being covered-up from the public before the purchase.
More news to follow on this front if the mod permits.

Thanks again for all the input fellas.

Tim (Mr2Tim)
--------------------------------------
89 SC Mr2 Race Prepared/Street Licensed
88 SC Mr2 Street car
87 NA Mr2 Hardtop Drag Car
87 NA Mr2 Street Car Sunroof
87 V6 Fiero AutoX-street
95 Camaro Z-28 Race/Street
73 Triumph Spitfire-Rally
83 Celica Autocross Prepped
70 Chevy Nova 396/325HP-Drag
64 Olds F-85 Drag Car
 

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You should be able to identify the heater wires by wire color as identified in Imperial Crown's post above.

I think everyone on this board is sympathetic toward the concern of non-USA made parts. We are all going through this with the aftermarket parts and some really are inferior or have built in obsolesence. I don't recall anyone having so many failures in a row with the O2 sensor. It just seems like it has to be an intermittant connection on the heater circuit to the sensor, especially since you are not having performance issues.
 

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I had a similar problem with a cam sensor (aftermarket), that ended up costing me about $800 to fix based on the CEL light coming on. Nothing wrong with the sensor, engine, or computer per se, it was the material the casing was made out of. Evidently it was able to both fire the cylinder and track to the computer to identify a missfire (all cylinders). It took a trip to the dealership to figure it out, but did teach me to go to the dealership when it comes to electronic replacement parts. This many failures requires looking outside the box for the reason.
 

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If you have been using OEM brand O2 sensors and you are on the 5th one, I doubt that the O2 sensor itself is the problem.
P0135 doesn't automatically mean that the sensor is bad. Get a good service manual and solve for the other 'possible causes' up to and including the PCM.
There may be no symptoms other than the 'ck eng' light. DIAGNOSE!
 

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Discussion Starter #11
Back again,

the Denso which is assembled in America with Chinese parts failed at about 4 weeks. Thusfar all the critical "heater" parts appear to be the culprit all made in China.

I'm going to reset the CEL and see if the code reaccurs immediately.

Since it is heater function of the O2 the failure apparently only effects warmup and not normal driving once the sensor this condition is not critical to me at the mechanic.
However the CEL seems to drive the wife crazy. :)
This will eventually be critical to the mechanic (me)
 

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You are replacing the (1/1-upstream) O2 sensor mounted in the exhaust manifold and not the one under the car or in the cat pipe, correct?
The 2 white heater wires should read around 3-7 ohms. If they aren't open, the O2 should still be good.
 

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Don't keep replacing sensors. If they are truly failing, then either there is still a wiring problem, or the engine is causing the sensor failure. There is virtually zero possibility of all of these sensors being defective.
 

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I would get the wiring diagram to determine the power going to the heater portion of the sensor, which appears to be the problem. It could be a bad wire or whatever else in the line which initiates the heater to start.
 

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time to start checking wiring.
5 sensors?
not a chance.
i put in the cheapest sensors i can find.
if it is in fact the heater going out,then put a resistor in place of the heater,it should fool the ecm ,taking care of the cel.
 

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The schematic symbol for the heater in the O2 sensor is a square wave pattern with an arrow through it. This is a thermistor-controlled heater and changes resistance greatly with temperature. This gives it a self-regulating characteristic for a fast warm up time and self-controlled current flow once it reaches operating temperature. It would be difficult, if not impossible for a wiring or PCM short to actually damage an O2 sensor heater.
A standard resistor probably won't fool the PCM and will need to interact with what the PCM sees for an O2 signal voltage. It will set the P0135 code again. The 3-7 ohm spec is for room temperature only.
The heater is fed 12 volts once the ASD relay turns on and is regulated/monitored on the ground side through the PCM. If it isn't the wiring and it's certainly not the sensor, you may be looking at a reman or good used PCM to fix this. Follow Possible Causes in post #6.
 

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I see My2Tim has been fighting this problem for two years now. We just recently got these same codes. It was also time for a timing belt change, so we sent the car into the mechanic to change both oxygen sensors, and the timing belt water pump stuff.

Prior to dropping the car off the car ran great, the only indication that something was wrong was the CEL being on. Mechanic says the ground for the Oxygen sensor heater is bad. I believe the ground is inside the engine computer right? This seems like something easy enough to look into and fix and I didn't want someone hacking up the wiring harness as, he suggested just bypassing the ground with another wire. So I tell him to not mess with the wiring and pick the car up. Upon picking the car up and on the way home I discovered that if you press the accelerator pedal half way down or more, the CEL flashes and the car bucks. I believe this indicates misfires. i have replaced the plugs and wires many times on these cars to fix misfire. So I did that, without improvement.

My question is if any one knows if there is a common place these turbo PT cruisers ground both O2 sensors out? and if the timing belt change could have caused the bucking, since there was none before, even with the same CEL codes/oxygen sensor problem... I do not think the CEL is related to the bucking. I did find some loose bolts on the cruise control actuator, and wonder if he left something else off, although I haven't found anything.

During the visist to the mechanic both torque motor mounts were replaced as well as the driver side axle.
 

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They are the codes for a bad heater circuit ground, I will have to check when I get home, I can't remember the numbers off hand.
 

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check engine gound.
 
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