My 2001 Vogue just failed its Contrôle Technique (CT = French MOT) on emissions amongst other things. It's only done about 1K miles after fitting a fully reconditioned engine by V8 Developments. The failure was

Lambda 1.128 when the acceptable level is 0.97 - 1.03

It also failed on holes in the exhaust system. The tester told me that there were lots of holes over the whole system after the cats. I haven't been underneath to look but it definitely does sound a bit throatier than it should.

I'm not sure of the relevance but the only error picked up by my Nanocom is P1035 OXYGEN SENSOR HEATER UPSTREAM

Any ideas?

You've only got upstream sensors anyway, only US spec cars have downstream as well. I would suspect that once the holes in the exhaust are fixed, the emissions will come down too. My daughter's Toyota failed on emissions and blowing exhaust, once the exhaust was fixed the emissions also came down.

I will fit the new exhaust & cross my fingers. Annoyingly the only way of testing emissions is to pay for the CT to be done.

Any thoughts on the P1035 error? Is it a dead or dying O2 sensor?

the O2 fault is specifically for the sensor heater. Suggesting either a wiring fault or a dead sensor.

P0135, not P1035.

P0135 does point to the lambda sensor's heater circuit. With this error code the lambda sensor may output correct signal or not when the lambda sensor is hot enough (the heater normally makes it hot, the error says the heater won't be working) and the ECU may run in closed loop mode (so attempt to correct mixture based on lambda sensor signal) or not (may run in open loop mode and ignore lambda sensor signal). But it does all point to you needing to change that lambda sensor or fix it's wiring.

Sometimes a lambda sensor with failed heater circuit will output correct signal when hot enough but it might not be hot enough when the engine is just idling.

If there's a problem with the heater circuit the heater circuit could be shorted to the signal circuit, which will mess up signal.

Lpgc wrote:

P0135, not P1035.

P0135 does point to the lambda sensor's heater circuit. With this error code the lambda sensor may output correct signal or not when the lambda sensor is hot enough (the heater normally makes it hot, the error says the heater won't be working) and the ECU may run in closed loop mode (so attempt to correct mixture based on lambda sensor signal) or not (may run in open loop mode and ignore lambda sensor signal). But it does all point to you needing to change that lambda sensor or fix it's wiring.

Sometimes a lambda sensor with failed heater circuit will output correct signal when hot enough but it might not be hot enough when the engine is just idling.

If there's a problem with the heater circuit the heater circuit could be shorted to the signal circuit, which will mess up signal.

Thanks for picking up the typo. It was a 20 mile drive to the test centre & they tested soon after I arrived so I think that the sensors were probably warmed up OK whether the heaters were working or not.

How difficult a job is replacing the sensors? Looking at RAVE it's just a question of wriggling under the car & unscrewing them from the cats. I guess I can find the correct size of spanner from the replacement.

Any recommendations for which sensors to use. There is a wide range of prices. Is this one of those cases like with the MAF that buying anything other than Bosch is a waste of money? https://www.lrdirect.com/mhk100940-sensor-lambda

The wire is a pest. Can't recall if the connector is small enough to go through a ring spanner of the right size for the hexagon. If it isn't best to get a proper split ring spanner or split socket with offset drive so as to have good purchase on the sensor body.

The big imponderable is how tight years of heating and cooling have made the sensor in its thread. I'd need to be confident that it's not gone super tight before trusting to an open end.

Bought a relatively inexpensive Hilka branded set of two offset square drive split sockets to pull the Lambda sensor on my Yamaha GTS which fitted far better than I expected given the price and worked well. Set comprises one 1/2" drive and one 3/8" drive. But that Yamaha is silly low mileage, despite being 30 years old, and the sensors are known to come out easily if factory fitted.

I'd expect the P38 sensors to put up more of a fight so would push the budget to cover a proper split ring spanner from a good make.

I was impressed with the Gedore ones I bought to do the oil coolers and pipes last year. £60 odd for two spanners isn't cheap but they fitted really well and got things undone without drama where an open ended spanner would almost certainly have distorted the hexagon unions. Gedore claim to make their spanners more accurately than other makes. Something I'm willing to believe on the evidence of that pair.

Clive

Stilsons.....

Aren't they usually 7/8 hex?

Agreed with Gilbert Stilsons are great for rusted hex's.

You can buy a socket from Halfords specifically designed for removing lambda probes... Obviously deep, it has a slot along the length, the wire protrudes through the slot. The top of the socket has it's own hex, so even if there isn't enough space to use the socket with a ratchet/bar/extension you'll probably still be able to get on it with a spanner. I've got a couple, very good.

Tried all sorts of tools over the years for getting lambdas out of many models of car, made my own special tools for some models of car (usually just the cut-off end of a ring spanner welded to an extension, a slot cut in the ring for the wire to go through, but different angle between ring and extension for different cars).

Is there enough room to use a Stilson? The sensors are on top of the cat. As engine has been recently replaced & the post-cat exhaust system needs replacement it might easier to remove the cats before applying penetrating oil & heat to the old sensors.

Easier said than done. To get the cats and downpipes out, you need to take the gearbox crossmember off.....

Wait until you have the new exhaust fitted and you will be able to look at the lambda on the Nanocom. If you check it now and make a note of the readings, then check again after the exhaust leaks are no longer there.

Gilbertd wrote:

Easier said than done. To get the cats and downpipes out, you need to take the gearbox crossmember off.....

Wait until you have the new exhaust fitted and you will be able to look at the lambda on the Nanocom. If you check it now and make a note of the readings, then check again after the exhaust leaks are no longer there.

Good point. Replacing the sensor doesn't look like a simple job so if I can avoid it I certainly will.

i just replaced my sensors , they came out very easy with a 17mm open end spanner, gems. the usual would apply , check that the plugs are not dirty or corroded or damage to warring. i think you can check the heating circuit on the sensor with a multi meter . 5 minute job if it just undoes.

mad-as wrote:

i just replaced my sensors , they came out very easy with a 17mm open end spanner, gems. the usual would apply , check that the plugs are not dirty or corroded or damage to warring. i think you can check the heating circuit on the sensor with a multi meter . 5 minute job IF it just undoes.😀

When Jamie at the Auto Barn in Sudbury fitted my stainless steel exhaust he also replaced both lambda sensors with new Bosch ones. Apparently one of the old one put up a fight & he d to re-tap the thread to fit the new one. I have the CT booked for three days time when I will get the definitive answer as to whether the emissions are now OK.