Exhaust Leak, P0402 Error, and MOT

alihd

I bought a 1.3 VVTi Yaris 2008 with almost 100K mileage.
The last MOT had an advisory for "minor engine leak", but I didn't notice too much noise when I bought it.

• Catalytic converter: A few days after buying the car  I realised the engine check light is on. I got an OBD2 scanner and realised the error is P0402: catalyst system efficiency below threshold (Bank 1). Since then I have cleared the code a coupe of times, but it reappears after a few days.

• Exhaust Leak: Last week I brought the car to a service shop to change oil (they only change oil and tyres). When the car was on the lift, one of the staff showed me where exactly the leak is. It's right under the gearbox. He wire-brushed the pipe and cleaned the carbons to show me the hole and suggested that I buy something like QuikSteel paste to fix it myself. I haven't done it yet, and now that the hole is cleaned, it makes more noise.

My MOT is in October so I am not really willing to pay too much for the cheap car I just bought, as more issues could arise by the MOT time and I can decide by then what is worth doing. Nonetheless, I wonder:

1. Does driving the car whilst it has a P0402 error AND exhaust leak cause any damage to the engine? 
2. Will I fail the MOT for either of these issues?
3. How likely is it that the catalytic converter P0402 code is due to the exhaust leak? (so that fixing the pipe will resolve P0402? 
4. In case I want to fix the exhaust, are any of the DIY solutions likely to last for 5 months (until my MOT time)? I found a lot of options like QuikSteel paste, metal bondage + glue, or fabric bondage, all costing belong £20, but the reviews say each of them haven't lasted for some people. It's very confusing which one is the best.
   

Cotswoldtony

Hi, your corroded exhaust needs replacing and the error code is probably due to the leak with incorrect oxygen levels picked up by the engine sensors.  It will fail the M.O.T if not fixed also it may break if you hit a pot hole or speed bump.

AdrianC

alihd said:

I bought a 1.3 VVTi Yaris 2008 with almost 100K mileage.
The last MOT had an advisory for "minor engine leak", but I didn't notice too much noise when I bought it.

• Catalytic converter: A few days after buying the car  I realised the engine check light is on. I got an OBD2 scanner and realised the error is P0402: catalyst system efficiency below threshold (Bank 1). Since then I have cleared the code a coupe of times, but it reappears after a few days.

• Exhaust Leak: Last week I brought the car to a service shop to change oil (they only change oil and tyres). When the car was on the lift, one of the staff showed me where exactly the leak is. It's right under the gearbox. He wire-brushed the pipe and cleaned the carbons to show me the hole and suggested that I buy something like QuikSteel paste to fix it myself. I haven't done it yet, and now that the hole is cleaned, it makes more noise.

My MOT is in October so I am not really willing to pay too much for the cheap car I just bought, as more issues could arise by the MOT time and I can decide by then what is worth doing. Nonetheless, I wonder:

1. Does driving the car whilst it has a P0402 error AND exhaust leak cause any damage to the engine? 
2. Will I fail the MOT for either of these issues?
3. How likely is it that the catalytic converter P0402 code is due to the exhaust leak? (so that fixing the pipe will resolve P0402? 
4. In case I want to fix the exhaust, are any of the DIY solutions likely to last for 5 months (until my MOT time)? I found a lot of options like QuikSteel paste, metal bondage + glue, or fabric bondage, all costing belong £20, but the reviews say each of them haven't lasted for some people. It's very confusing which one is the best.
   

That exhaust has already been bodged once. What you're looking at is some very shonky welding where the pipe's fractured previously.

The fault code is telling you the post-cat oxygen sensor is reporting that the exhaust gas's oxygen levels are not what it would expect from a healthy cat. That's because of the leak.

And, yes, the car will fail the MOT. The exhaust leak is a fail, and quite likely the emissions will be.

A proper fix is to replace the exhaust. 13 years is a good life for an exhaust.

HansOndabush

Cut the top and bottom out of a tin can. Cut down the side of the can. Wrap the can around the leak with plenty of firegum paste inside. Tighten can down hard using jubilee clips. That fix is as good as anything you can buy and a lot cheaper.

red_eye

alihd said:

I bought a 1.3 VVTi Yaris 2008 with almost 100K mileage.
The last MOT had an advisory for "minor engine leak", but I didn't notice too much noise when I bought it.

• Catalytic converter: A few days after buying the car  I realised the engine check light is on. I got an OBD2 scanner and realised the error is P0402: catalyst system efficiency below threshold (Bank 1). Since then I have cleared the code a coupe of times, but it reappears after a few days.

• Exhaust Leak: Last week I brought the car to a service shop to change oil (they only change oil and tyres). When the car was on the lift, one of the staff showed me where exactly the leak is. It's right under the gearbox. He wire-brushed the pipe and cleaned the carbons to show me the hole and suggested that I buy something like QuikSteel paste to fix it myself. I haven't done it yet, and now that the hole is cleaned, it makes more noise.

My MOT is in October so I am not really willing to pay too much for the cheap car I just bought, as more issues could arise by the MOT time and I can decide by then what is worth doing. Nonetheless, I wonder:

1. Does driving the car whilst it has a P0402 error AND exhaust leak cause any damage to the engine? 
2. Will I fail the MOT for either of these issues?
3. How likely is it that the catalytic converter P0402 code is due to the exhaust leak? (so that fixing the pipe will resolve P0402? 
4. In case I want to fix the exhaust, are any of the DIY solutions likely to last for 5 months (until my MOT time)? I found a lot of options like QuikSteel paste, metal bondage + glue, or fabric bondage, all costing belong £20, but the reviews say each of them haven't lasted for some people. It's very confusing which one is the best.
   

All those bodges are only temporary they could last 1 day or 10 years. If you have a power flow branch near by they can weld tube to the cat and sleeve it to the rest, £40-60.
i used to do loads of these.

if it has a sensor after the hole then patching the hole should fix your p code.