Check Engine Light

Technical Area Engine, Transmission, Exhaust etc
2

Evenin all,

 

I have a P2097 fault code on my 2006 2.0 mk3. I have cleared it a couple of times and it has returned, usually about 100 miles or so later and always while doing about 65-80mph on the motorway. Instinctively I bought a replacement rear O2 sensor which I have yet to fit but I thought it would be a good idea to ask to see if there were any on here that had experienced this particular error while I still have the chance to return it. 

 

I have Torque on my phone and a bluetooth OBDII reader that logs whats going on as I drive. It produces massive spreadsheets with data every half a second but I can’t decipher the issue, I can upload should anyone be interested.

 

Freeze frame information: 
------------------
Fuel Status = 0 byte
Engine Load = 46.275 %
Engine Coolant Temperature = 69 °C
Fuel Trim Bank 1 Short Term = -1.562 %
Fuel Trim Bank 1 Long Term = 0.781 %
Intake Manifold Pressure = 9.137 psi
Engine RPM = 3,302.5 rpm
Speed (OBD) = 75.186 mph
Timing Advance = 42.5 °
Intake Air Temperature = 7 °C
Mass Air Flow Rate = 27.96 g/s
Throttle Position(Manifold) = 21.961 %
Run time since engine start = 2,324 s
EGR Commanded = 67.059 %
Distance travelled since codes cleared = 109.361 miles
Barometric pressure (from vehicle) = 14.939 psi
Catalyst Temperature (Bank 1,Sensor 1) = 688.3 °C
Voltage (Control Module) = 13.917 V
Engine Load(Absolute) = 43.529 %
Commanded Equivalence Ratio(lambda) = 1.031 
Relative Throttle Position = 12.941 %
Absolute Throttle Position B = 22.353 %
Accelerator PedalPosition D = 36.078 %
Accelerator PedalPosition E = 24.706 %
3

Another freeze frame

Freeze frame information:

Fuel Status = 0 byte
Engine Load = 38.824 %
Engine Coolant Temperature = 69 °C
Fuel Trim Bank 1 Short Term = 0 %
Fuel Trim Bank 1 Long Term = 2.344 %
Intake Manifold Pressure = 7.832 psi
Engine RPM = 2,859 rpm
Speed (OBD) = 65.244 mph
Timing Advance = 49 °
Intake Air Temperature = 8 °C
Mass Air Flow Rate = 19.58 g/s
Throttle Position(Manifold) = 20 %
Run time since engine start = 2,288 s
EGR Commanded = 55.686 %
Distance travelled since codes cleared = 123.031 miles
Barometric pressure (from vehicle) = 14.649 psi
Catalyst Temperature (Bank 1,Sensor 1) = 629.2 °C
Voltage (Control Module) = 13.92 V
Engine Load(Absolute) = 35.686 %
Commanded Equivalence Ratio(lambda) = 1.031
Relative Throttle Position = 10.588 %
Absolute Throttle Position B = 20.392 %
Accelerator PedalPosition D = 35.294 %
Accelerator PedalPosition E = 23.922 %

4

You can chase your tail on this one but the rear O2 sensor is advising that the mixture is wrong and it’s job is to measure what comes out the CAT.

 

The front 02 sensor sends a signal to the ECU which tells the fuel system to tweek the mixture. Therefore the order I would do them is front and if that does not fix it rear.

Betore you do anything check for slight exhaust weeps around the cat and go over all the rubber tubes around the inlet system looking for leaks.

There is no correct answer here and you need a O2 sensor socket to remove the O2 sensor. They are very tight and if you have not done one before, soak it in penitrating fluid and when it moves, stop and soak it again and wait for 20 minutes the remove slowley if required soak it again, if it is tight.

 

5

I’ll have a good check around tomorrow see if there is anything I’ve missed.

 

I’ve already changed the air filter and given the MAF sensor a clean. Hopefully I’ll find something amiss so I won’t have to spend £170 on a new front sensor

6

Rear sensor checks the cat is working. If the cat was the problem the light would come up straight away after you cleared it. It takes 100 miles and always at speed, vibration and heat on the sensor under those conditions is probably why it is failing. Of course other things play into this, high low fuel pressures but that is covered by the front sensor that appears to be ok, no fault code. Occasionally I have seen catalyst come apart and spin in their housing that would also trigger the light, however it would be rattling and loss of power as exhaust blocks. you have a sensor, I would be changing that first.

7

These sorts of problems are always annoying. I would rather the fault was instantly coming up. I could change either or both of the sensors but I still won’t know it’s cured for at least 100 miles and even then it might be the time it takes 300.

 

The rear sensor is by far the cheapest and I already have one so after I have had a good look around to check for leaks etc I’ll start with the plusgas.

8

No correct answer here as I have advised and as the other poster advised just our opinions.

In your case you have a rear O2 do that.

If that does not work, I can send you a 20k mile cat if you want that.

On the other hand try the front sensor.

“Suck it and see,” as they say.

9

That’s a very kind offer Drumtochty thank you. I may yet take you up on it 

 

In the meantime my back has just gone ping so getting under the car (or even in it) is somewhat painful so progress with this is going to be slow!

10

Rear sensor now changed. Plenty of plusgas and it just unscrewed. Now to see if it re-occurs. 

11

300 miles travelled and no light. So I declare this problem sorted. Thanks for all your contributions .

12

Hello Sir,

I’m another one whose engine light has come on (P0037) rear sensor. Please could you give a quick run down on how to replace it, as I’ve heard some say that you have to remove the passenger seat first?! Many thanks, Andy. PS I have the new rear sensor with lead and plug, and a 22mm O2 socket wrench…

13

Blimey, you dug this thread up didnt you!

Essentially it’s a sensor bolted into the side of the bottom of the manifold. You can access it from underneath. I’m not sure why you would want to remove the passenger seat. I sprayed penetrating oil over the threads of the sensor a day or two before removing it. You need a sensor removal tool and to be fairly supple and patient. I unplugged the sensor, unscrewed it from the manifold and then did the reverse to get the new one in.

Hope thats of some use, i cant remember much more as it’s been nearly 6 years

14

The plug for the rear sensor is under the carpet behind the seat. I think that you can get to it just about with the seat in situ.