Trouble code P1526 means: Air Bypass System
actually, this is the abv vent solenoid circuit. you must have a 2.3. the vent solenoid lives on the right bank. next to the egr valve, you will see a row of solenoids. the vent is second from the right(KJ03-18-741A). you can ohm the solenoid to see if it is bad, but i am sure it is. 26 is good, above 30 or 0 is bad. you should also change out the vacuum solenoid(4th from the right, KJ02-18-741A), they both go out about the same time, and they cost the same. dealer only. http://www.tascafordparts.com//index.do
this is your best bet for Mazda parts. lastly, if you are going to keep the car, you should also change out the vacuum lines and tees. but this is a big job.
Trouble code P1526 means: Air Bypass Systemcan i see some pics of the air bypass system
po421 is catalytic converter problem rear bank
The code PO404 on a 2000 Mazda Millennia 2.3 means that there is something wrong with how the vehicle is processing the oxygen it needs for combustion. This would mean an oxygen sensor or solenoid is bad. This vehicle has two oxygen sensors.
Call autozone and they can help with the code.
Trouble code P0715 means:Input/turbine speed sensor circuit malfunction
no sgc signal. cam position sensor
Trouble code P0401 means:Exhaust gas recirculation flow insufficient detected
remove the plastic cover that says miller cycle engine on it. right about where "engine" is, you will see it. it has a gold dashpot with vacuum lines
Trouble code P0720 means: Output Shaft Speed Sensor Circuit
typemake, model, code into your computer .i have a list of codes and there is no p1105 code, clear your machine and try again
variable resonance induction solenoids.solenoid not closing or opening
Trouble code P0303 means:Cylinder 3 misfire detected