I hope not to tire any of you here with my second car. I am charged with caring for a 2002 VW Jetta, V6, automatic transmission, on which I am reading error codes P0030 and P0811 with Mulfunction Indicator Light on. The car has 82k miles on it.
P0030 seems to be for Bank 1 Sensor 1, but I have not found an authoritative source. I am seeing P0811 being discussed mainly with relation to manual transmissions, but there are mentions of some sensors, and even ATF, as independent causes. I believe the ATF was changed less 5k miles ago, but I need to confirm. The ATF was extremely dirty at the time.
I will highly appreciate insights as to what the codes indicate.
@db4690, P0030 is what the code reader actually shows. I have searched and found some literature on the same, e.g. see here: http://www.obd-codes.com/p0030
I have seen descriptions like: HO2S Heater Control Circuit Bank 1 Sensor 1. Is this the same as B1S1 air-fuel ratio sensor (or does the prefix “HO2S Heater Control Circuit” indicate a different B1S1)? While I am keen on both problems, I am a lot more concerned about P0811.
The P0811 code description is “Excessive clutch slippage”.
Your P0030 code description is correct. There is a separate code for H02S Heater Control Circuit Low B1S1 (P0031), and H02S Heater Control Circuit High B1S1 (P0032). I would begin by checking the resistance of the heater element in that O2 sensor (Bank1 Sensor 1).
There are clutch packs inside the transmission and based on the slippage code along with your prior comment about the fluid appearing to be extremely dirty, I would have some concern about the transmission nearing the end of its life.
The fluid was dark due to slippage of the friction material (clutch packs) and once this starts it’s usually downhill from there.
My comment is applicable to any automatic transmission; it’s not a VW only thing.
Slipping clutches can be due to failure to change the fluid regularly, aggressive driving, engine overheating and/or engine coolant mixed with the transmission fluid, aged/leaking seals inside the transmission, electronic glitches, and so on.
Generally this involves rebuilding or replacing the transmission but due to the expense involved I would certainly recommend having a reputable independent transmission shop scan it and take a look at it first. Do not take it to a chain type of transmission facility like AAMCO, Cottman’s, etc.
Extremely dark fluid usually points to excessive friction material from the clutches though.
@ok4450, I pulled this car off the driveway the other day and it let out a big spill of some liquid (I bet ATF) . So I am thinking aged/leaking seals are most likely the cause. I think I will have to tow the car to a garage.
Was the proper trans fluid used?
There is a chance some universal stuff was used and putting in the fluid VW specifies will make the trans happy again.
@circuitsmith, how I love to hear some hope! Many thanks! Unfortunately any history for this car is scanty. The car has fallen into my wife’s hands after her sister cannot drive. For several years I have checked the car occassionally, and each time I have said “this car has a transmission problem”. But it has been checked by good mechanics severally, even had a transmission flued changed I think a couple of years ago, but no one has ever said that it has indeed turned up a Transmission diagnostic error code. Then just recently I drove it, and felt it had gotten too bad. I tested it with my cheap reader … and there it was, P0811.
The car was just coming from a shop, and P0811 was not among the error codes the shop read. So I am wondering whether their readers have always missed this error code, or if the error code became readable just before I made my reading. What a coincidence that would be!
Anyway, now I would like to fill up with ATF and see what happened. But I am challenged … I cannot find where this car’s ATF is supposed to be filled from. Would you have directions for me here? The ATF system is closed for this car, in that there is no dip stick, but there has to be somewhere to fill it through.
As for Code P0030, I suspect the culprit is a breather hose that I find broken, connecting the intake (just close to the MAF Sensor location) and the engine. I will need to track this hose and replace it in full. It is a hard hose and there is hardly a way to repair it.