I have 2007 MCS with 198,000 km (118,00 miles) on the highway yesterday cruising at 160 km/hr (100 MPH) when I suddenly lost power and went into limp mode. Got home and pulled the following codes: P1497-“Downstream Throttle Air Leak”, P0130-“Before Catalyst Oxygen Sensor, Electrical: Nernst Cell Resistance or Ceramic Temperature Implausible, Wiring or Heater Fault”, followed by several codes for cylinder misfires.

So I say to myself that this should be an easy fix; just find the “downstream throttle air leak”. But I can’t find an air leak anywhere. I have cleared the codes and the engine runs like crap. I plan to do a compression check to ensure everything is fine internally but I need a long reach adapter for my compression tester to reach into the recessed spark plug holes.

Any advice or suggestions as to possible cause is much appreciated.

 

if i remember correctly, i had that P01497 code. there is an air pipe that forks out behind the air intake into the plastic trim piece. check if it is tight or no holes in it. also, make sure all clamps are clicked in and fittings are tight.

 

What O2 sensor do you have? Do you hear a leak anywhere? Any hissing coming from your valve cover possibly? It's not uncommon for them to crack. MINI does have an "updated" one out if yours has never been replaced.

A few threads with that code that ended up being the valve cover.
https://www.northamericanmotoring.co...cuum-leak.html
https://www.northamericanmotoring.co...g-at-idle.html

This one is a bit more detailed, but with detailing with P1497 they came to find their timing was off:
https://www.northamericanmotoring.co...yest-thou.html

Some more info here:
https://www.northamericanmotoring.co...-pls-help.html

Do you have the capability to do a smoke test? This might help you find a leak if there is one as well. Also, our compression tester comes with an adapter, not sure if it'll meet your needs but you can read the details of it here. Anyways, hope this helps a bit and let us know what you find out.

 

The PCV vent tube at the back of the valve cover is a usual culprit for the 1497 code, but you need to diagnose that. I've seen timing problems cause it as well.

As for the lambda sensor; is there oil leaking down the wiring harness into the connector? We see a lot of these cars with oil ingress into the connector that causes internal faults in the sensor.

We've got both items in stock and ready to ship, give us a call if you have any questions or need any help in the diagnostic.

Detroit Tuned
586-792-6464

 

I was away for a couple of weeks so the car sat in the shop. Last night after work I got around to doing a compression test. Zero on cylinder 3. I’m suspecting a bad exhaust valve.
I bought the car in the spring as a repair project. It had a small chunk missing from an exhaust valve in cylinder 1. I replaced the valve and made some other minor repairs and the car ran well all summer but burned a significant amount of oil (about a liter every 1000 kilometers). Should have replaced all the valves at that time but money & time are tight.