P0420

[McSmallface]

So I picked the car up knowing there was an "intermittent" EML showing, plugged it in and it's the apparently all too common P0420, I've done some trawling and apparently the common culprits are main cat, main cat 02 sensor or air leak.

The car has just had a new main cat (PO had it done to get through recent MOT due to emissions fail) and I've done the vac trick to check for air leaks but all seems good so am I safe to go ahead and buy a new post main cat O2 sensor or is there something else I may be missing?

[1979scotte]

What sort of cat did he have fitted?
OEM equivalent or a sports cat?
If its a less restricted 100 or 200 cel cat could still give you the same code.
Also quite often the sensors do go kaput when messed with.
Is it a stock denso sensor? In the past other makes have caused issues.
Probably you'll have to suck it and see unfortunately.

[Ardent]

What ^^^^  said.

Assuming new cat is upto the job. And no leaks. Only leaves the sensor.

And if same sensor removed out old cat and put in new cat. More than enough to upset it.

[Ardent]

Sparkplugs.co.uk I find are reasonable. Amazon if your timing is good.

Dox0602 (double check)

[JB21]

Just had this fault code ping along with P0410 – Secondary air injection (AIR) system -malfunction after jet washing the car, weird.

Deleted them via torque pro and they haven't returned as of yet.

[McSmallface]

It's a cats2u cat so stock setup, the sensor is denso but it looks old so maybe the swap has upset it. I'll pop a new one on and see how we go.

It does take a good 20 odd miles (30-60 mins) of driving before it comes back on after clearing it.

[Ardent]

It does take a good 20 odd miles (30-60 mins) of driving before it comes back on after clearing it.

Yep.

[Ardent]

Just had this fault code ping along with P0410 – Secondary air injection (AIR) system -malfunction after jet washing the car, weird.

Deleted them via torque pro and they haven't returned as of yet.

Just checking. It is a 1zz engine you have?

[JB21]

Just had this fault code ping along with P0410 – Secondary air injection (AIR) system -malfunction after jet washing the car, weird.

Deleted them via torque pro and they haven't returned as of yet.

Just checking. It is a 1zz engine you have?

Sorry yeah, 2zz in mine.

[Ardent]

I freely admit to a bit air fist pumping for sussing that out.

Had chance to explore the rev range?

[Ardent]

I freely admit to a bit air fist pumping for sussing that out.

Had chance to explore the rev range?

Note to myself, must pay more attention. Only looked at what was posted. Not by whom. Thought was original poster. Fist pump seems a bit deflated now. Back in my box.

[shnazzle]

Change sensor. Monitor. Go from there.
On the right path.

@JB21 wrong error code mate Yours will likely pop up from time to time. Part/parcel of 2zz conversion

[McSmallface]

Great cheers I'll pop a new one on, where is the best place to get a new denso? Cheapest I've found is £85

[shnazzle]

Great cheers I'll pop a new one on, where is the best place to get a new denso? Cheapest I've found is £85

As per above it's a Denso DOX-0206

https://www.sparkplugs.co.uk/denso-lambda-sensor-dox-0206

Alternatively https://www.sparkplugs.co.uk/denso-lambda-sensor-dox-0109  if you're OK with crimping (not soldering!) wires.

[Alex Knight]

Just had this fault code ping along with P0410 – Secondary air injection (AIR) system -malfunction after jet washing the car, weird.

Deleted them via torque pro and they haven't returned as of yet.

Did you start the engine from cold, then shut it off again relatively quickly?

[McSmallface]

Great cheers I'll pop a new one on, where is the best place to get a new denso? Cheapest I've found is £85

As per above it's a Denso DOX-0206

https://www.sparkplugs.co.uk/denso-lambda-sensor-dox-0206

Alternatively https://www.sparkplugs.co.uk/denso-lambda-sensor-dox-0109  if you're OK with crimping (not soldering!) wires.

Why no to soldering?

[Carolyn]

Great cheers I'll pop a new one on, where is the best place to get a new denso? Cheapest I've found is £85

As per above it's a Denso DOX-0206

https://www.sparkplugs.co.uk/denso-lambda-sensor-dox-0206

Alternatively https://www.sparkplugs.co.uk/denso-lambda-sensor-dox-0109  if you're OK with crimping (not soldering!) wires.

Why no to soldering?

The wires on these are coated and don't like solder. It doesn't take properly.

[JB21]

Just had this fault code ping along with P0410 – Secondary air injection (AIR) system -malfunction after jet washing the car, weird.

Deleted them via torque pro and they haven't returned as of yet.

Did you start the engine from cold, then shut it off again relatively quickly?

Indeed I did mate

[McSmallface]

Great cheers I'll pop a new one on, where is the best place to get a new denso? Cheapest I've found is £85

As per above it's a Denso DOX-0206

https://www.sparkplugs.co.uk/denso-lambda-sensor-dox-0206

Alternatively https://www.sparkplugs.co.uk/denso-lambda-sensor-dox-0109  if you're OK with crimping (not soldering!) wires.

Why no to soldering?

The wires on these are coated and don't like solder. It doesn't take properly.

Thanks for the heads up as I always solder all my connection so I'll buy one with the connector instead

[McSmallface]

Are the manifold o2s the same as the cat o2?

[1979scotte]

Are the manifold o2s the same as the cat o2?

Sensors are all the same but the cat sensor has a longer lead

[McSmallface]

Ah right, I was going to suggest swapping one of the manifold o2s over to see if it throws up a code on the manifold instead of the cat to diagnose if the cat sensor was gone but if they tend to die when messed about with I won't tempt fate and remove the manifold o2

[Alex Knight]

Just had this fault code ping along with P0410 – Secondary air injection (AIR) system -malfunction after jet washing the car, weird.

Deleted them via torque pro and they haven't returned as of yet.

Did you start the engine from cold, then shut it off again relatively quickly?

Indeed I did mate

Happens to me also.

The Celica ECU is looking for the secondary air pump which doesn't exist.

You can just clear the code and carry on.

[Dev]

Great cheers I'll pop a new one on, where is the best place to get a new denso? Cheapest I've found is £85

As per above it's a Denso DOX-0206

https://www.sparkplugs.co.uk/denso-lambda-sensor-dox-0206

Alternatively https://www.sparkplugs.co.uk/denso-lambda-sensor-dox-0109  if you're OK with crimping (not soldering!) wires.

Why no to soldering?

The wires on these are coated and don't like solder. It doesn't take properly.

Thanks for the heads up as I always solder all my connection so I'll buy one with the connector instead

I know people that have soldered their 02 wires without any issues however automotive or any mobile applications are generally not soldered because it isn't vibration resistant and they can fail over time due to fatigue. 
Most automotive wiring is done by using high quality crimp connectors because they are more reliable.
 The crimp connectors supplied in those kits collapse making an oxygen free connection.



 

[Carolyn]

I've known someone who has tried soldering the wires on a Denso O2sensor: Me!

It doesn't work.