Does anyone have any experience with lean and rich codes on their car? I have a persistent issue that I cannot get to the bottom of on my Hyundai santa fe 2001. I basically either get a p0171 lean code, or I get a p0172 rich code if I switch the O2 sensors around (both sockets are the same for upstream and downstream so hard to know which is which). Either way something is messed up. When we got the car it had a lot of receipts for new parts attempting to fix the issue bit no cigar (we paid peanuts for it). However after checking over everything the only thing that sticks out is that I can now see the MAF sensor is a cheapo Chinese copy and not the original Bosch. So I'm thinking that could be messing up the fuel trims. I have no air leaks, I've fitted a new fuel pump, new O2 sensors. Checked all air lines and fuel lines for kinks and nothing... Car drives ok, had mileage is so so and maybe lacking some power. I also blocked off the egr in case that was the culprit but no cigar...
Rich and lean codes nightmare
- Thread starter NinetyOne
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Soldato
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What engine do you have?
Soldato
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Had this on my 2005 E Class, it was the MAF sensor playing up.
Soldato
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I'm no expert but this website:
https://www.delphiautoparts.com/gbr/en/resource-center/making-sense-your-sensors-maf-sensor
Says a failing MAF sensor can cause an engine to run rich or lean, so this might explain your observation when you swap the oxygen sensors around.
https://www.delphiautoparts.com/gbr/en/resource-center/making-sense-your-sensors-maf-sensor
Says a failing MAF sensor can cause an engine to run rich or lean, so this might explain your observation when you swap the oxygen sensors around.