P0136 pd Malfunction

ezchomak · Post by **ezchomak** » 24 Jul 2010, 00:10

I have a '99 S70 and have just replaced both O2 sensors after getting codes P0135 and P0136. The new o2 sensors are now in the car and I am still getting P0136 as well as P0136 pd but no longer code P0135. My understanding about the difference between a "pd" or pending code and a regular DTC (diagnostic trouble code) is that a pending code indicates that the code has not occurred enough times for the code to "mature" into a full-blown DTC while a DTC is set when a fault is present for a sufficient amount of time. How can I be getting both at the same time? I would think that would be impossible.

If I clear the codes, the CEL will come on again after I've driven a mile or so. What could this mean? Will the CEL go out for good after 40 warm-up cycles if the o2 sensors are good? Could it be a simple problem such as a blown fuse connected to the offending sensor (Bank1 Sensor 2) that would be cheap and easy to fix (please, oh please!)? Assuming the brand new o2 sensors are good (the P0135 code went out right away but not the P0136), what else could be happening to generate this code?

Thank you much!

Post by **Ozark Lee** » 24 Jul 2010, 05:59

9 times out of 10 P0135 is a vacuum leak and not an O2 sensor problem at all. The P0136 is a rear sensor limit code.

What brand and model of O2 sensors did you replace them with?

Anything but OEM Bosch is often trouble but you may be able to force them back into range by pulling a battery cable for 10 minutes or so to reset the adaptive ranges in the ECU. You will need to know your radio code.

...Lee

vincent99v70 · Post by **vincent99v70** » 24 Jul 2010, 20:31

Got the same problem and can't pass smog, any hints?
Did use BOSCH sensors.

Post by **FlyingVolvo** » 24 Jul 2010, 20:40

vincent99v70 wrote:Got the same problem and can't pass smog, any hints?
Did use BOSCH sensors.

Were they the Bosch OEM ones or the Bosch "Universal" ones?

These cars are very picky...

vincent99v70 · Post by **vincent99v70** » 24 Jul 2010, 20:47

116591 miles mostly freeway, could I need a new catconverter?
Hate to think about that.
Bosch box, sensors stamped VOLVO, black and gray connectors, challenging to find in SOCAL.

850tech · Post by **850tech** » 24 Jul 2010, 21:10

Faulty circuit, faulty rear O2S, or exhaust leaks are most likely, although a cat is possible it is not the most common cause.

vincent99v70 · Post by **vincent99v70** » 24 Jul 2010, 21:14

Being challenged here, as both sensors are in front of cat.
Is this a problem that's gonna be worth more than my beloved V70?

Post by **Ozark Lee** » 24 Jul 2010, 23:37

both sensors are in front of cat.

That is not supposed to be like that - what has been modified? Sensor 1 should be in front of the cat and sensor 2 should be behind it. I have heard of people straight piping the cat and then adding an extender nipple to trick the rear sensor to turn the CEL off but I have never done it.

...Lee

Post by **FlyingVolvo** » 24 Jul 2010, 23:41

Might be a little confusing, on the Gen 1 cars, the rear O2 sensors sort of plugs in right to the front part of the cat. It really does look like it's "in front" as well, because it isn't behind the large mass of the converter.

vincent99v70 · Post by **vincent99v70** » 25 Jul 2010, 09:57

That's the set up on mine, hence the confusion.