Vios Mixture Preparation Error

I'm having a mixture preparation error on my 2014 Toyota Vios with a gasoline engine. It has about 133,432 kilometers on it. Engine power is down, the check engine light is on, it runs rough, jerks when accelerating, and sometimes stalls at idle. I've replaced the spark plugs and checked the oxygen sensor for damage, but it's still happening. I'm thinking it could be the air-fuel ratio or the intake manifold. Anyone seen this before?

4 comment(s)

Sounds like a real pain. Something similar happened with my old Opel Astra. Check engine light was on, and the car felt like it was choking when I tried to accelerate. Did you properly check the oxygen sensor, beyond just a visual inspection?

When you say 'properly check' the oxygen sensor, what tests are you referring to? I looked for physical damage or loose connections, but I didn't do any electrical testing.

Right, I recall now! It was the fuel injectors. Symptomatically, it sounds very similar to what happened to me. What fixed the issue on my Opel was taking it to a workshop and having them run proper diagnostics to identify the defective injector. Based on the symptoms you are experiencing, I would strongly recommend seeking professional assistance, as the issue may involve one or more defective injection valves or injectors.

I appreciate you sharing your experience. Your suggestion to seek professional diagnostics and specifically investigate the fuel injectors is helpful. I'll schedule an appointment with a trusted mechanic to examine the injection system. It turned out you were right. Cost me 515€ to replace the defective injector, but at least the Vios is running smoothly again!

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