Suzuki SX4. Engine light.

I had the same problem ... my garage scanned it and it came up as P0420, which is catalyst system efficiency below threshold bank 1.

Change air filter! Cheapest way and solving problem! Subi

Oil light flashing oil level ok

My engine light came what u think the problem is

I fought this Po420 code, a couple of things to note, the O2 sensors clearly are mostly responsible for this error, I had cat checked, absolutely clean, I had map sensor checked and cleaned, made problem less frequent, but still popped up occasionally, replaced both front and rear O2 sensors, code still popped up, final verdict, grounding strap on exhaust manifold to chassis ground needs to be perfect for voltage stability in O2 sensor. If there is the slighest flucuation it can cause false code,P0420 as well as P0138 and P0139 . This is clearly a flaw with CPU circuit design and will never be rectified by Suzuki as they are out of US market. Be forewarned, don't pay $1000's for a Cat you don't need and that wont fix the underlying problem. I now have 204 K , same original Cat, runs great, get 33 mpg highway.

your garage has suspicious motives, known as “profits”. The Cat Con is expensive, and rather than find the real problem, they’ll almost always go for the most expensive fix.

My suzuki sx4 the refcouner those not respond wat would the problem be

I had problem a couple of times and was told not to use 91. Always use 95 petrol. Saying that my engine light just came on and I have not used 91 petrol?