MR2 Roadster Owners Club

I just have my mr from last week but it was on my driveway for 2 months without registration and finally got to it. was doubting because I have 3 cars on the road lol.

So i drive the car, everythings fine but its very slow, full throttle and still sluggish, i have an bluetooth obd with Torque app for android and did a diagnose, it gave 2 errors.

02 sensor heater circuit bank 1 sensor 1
02 sensor heater circuit bank 2 sensor 1

So its pre cat and after cat sensors I should replace?  Diagnose sensor and regulator sensor? or how its called?

Thanks for the help

Bank 1 Sensor 1 is the top, pre-cat sensor on the right hand side of the manifold (when you are standing at the back of the car looking forward with the engine in front of you)
DTC Codes:
P0135 Oxygen Sensor Heater Circuit Malfunction(Bank 1 Sensor 1),
P0130 Oxygen Sensor Circuit Malfunction (Bank 1Sensor 1)
P0133 Oxygen Sensor Circuit Slow Response (Bank 1 Sensor 1)

Bank 2 Sensor 1 is the top, pre-cat sensor on the left hand side of the manifold (when you are standing at the back of the car looking forward with the engine in front of you)
DTC Codes:
P0155 Oxygen Sensor Heater Circuit Malfunction(Bank 2 Sensor 1)
P0150 Oxygen Sensor Circuit Malfunction (Bank 2 Sensor 1)
P0153 Oxygen Sensor Circuit Slow Response (Bank 2 Sensor 1)

Thanks for the information

My codes are

P0135 and P0155

Your failures are for both of the sensors in the manifold.
The sensor after the main cat is bank 1 sensor 2, which you do not have a code for.

I would recommend only buying Denso sensors. The cheap copies you will end up replacing.

Quote from: "StuC"Your failures are for both of the sensors in the manifold.
The sensor after the main cat is bank 1 sensor 2, which you do not have a code for.

I would recommend only buying Denso sensors. The cheap copies you will end up replacing.

Thanks man, have few more questions

Is bosch brand good enough and is it because of the sensors that the car has less power ?

thanks

I would expect Bosch to be reputable. But I would recommend sourcing Denso.

Failed heater circuits in the sensors would not account for loss of performance.

Edit
Sparkplugs.co.uk or amazon for sensors.

DOX 0204 Denso ref

Quote from: "Ardent"I would expect Bosch to be reputable. But I would recommend sourcing Denso.

Failed heater circuits in the sensors would not account for loss of performance.

Edit
Sparkplugs.co.uk or amazon for sensors.

DOX 0204 Denso ref

Totally agree you can put a resistor on the two black wires going to the lambas to trick the ecu and as they are first sensors the exhaust warms the sensors up fast anyway

Continuing on from this thread...
All 3 of my sensors show the heating circuit error... isn't it unlikely for all 3 to fail??   (P0135,  P0141 and P0155 error codes)

Is there a maybe a common heating circuit I could check first before having to buy 3 sensors? a fuse or a relay ???

Oh, and I tried the resistor accross the black wires... made no difference    s:( :( s:(

Unusual to have 3 go at once, but not unheard of on a tired car where maintenance has lapsed or where cheapo sensors have been used ( not suggesting this in your case, just covering all bases   s:wink: :wink: s:wink:  )

You can check the integrity of the heater circuits quickly with a meter by unplugging each one. A dozen or so ohms across the black wires indicates that the heater filaments are present and correct. Low ohms (5ish) suggests incorrect aftermarket sensor, open circuit indicates knackered.

12 volts across the equivalent wires on the harness plugs (ignition on) indicates that they're getting power. If you do these checks it'll help pinpoint whether its a general circuit failure or 3 pooped sensors. Or a combination of scenarios across the 3 circuits.

Its possible to trace the wiring from the ECU to each plug but a bit of a pain, so find out if this is where you're heading before worrying about it.

As for fuses/ relays, I think  the O2s are part of the IG2 circuitry (perhaps someone will confirm?). Fuse and relay are therefore common to a number of control circuits so unlikely to be at fault if the car starts! The earth return is also shared before it gets back to the ECU .... so if your wiring is at fault its likely to be on the O2 sensor side of any junction with other sensor circuits.

Some good info there. I'll be sure to follow that up!
It certainly had been subject to little, if any, maintenace before I bought it!

As a side, its also an oil burner, I wonder if that could damage the O2 sensors ?

Quote from: "UKTony"As a side, its also an oil burner, I wonder if that could damage the O2 sensors ?

I'm running Bosch O2 sensors without complaint.

I have two oil-burners.
The oil burning seems to have no effect upon the manifold-mounted O2 sensors.
That is: Bank_1, sensor 1 and Bank_2 sensor 1.

Oil burning may eventually result problems with the main Catalytic Converter O2 Sensor (Bank_1, sensor 2)

Thanks oldMan.  I'll buy the front 2 sensors then and if they get rid of the codes I'll look at getting the after cat one.

Update on the sensors, i replaced all 3 and still nothing. What should I do now?

Thanks

Are you getting any error codes now?

Have you got a 12v live to the sensors   sounds like you got a fuse popped or relay  all the sensors share a live

Errors were still there then I reset them and now there are none, would they come back on ?

 Where can I find the fuse or relay?

Thanks guys

Have you given it s drive do 2 miles it will register them  again if there is a prob

Yes  I drove for about 20 minutes then I did a diagnose , still the same codes and after reset well I can check in a few hours when I finish work to see if the codes are back. Can someone help me out to check the fuse and relay related to it. I dont have a manual book so cant look it up.

Also before I changed the sensors, I was driving at the highway and I noticedthat the car didnt respond well, full throttle and the revs went down for a second and then up....

Thanks

How long does it normally take the car to clear a P0135 by itself? I just replaced it but I have no idea if it's working or not.