2003 Chevrolet Suburban 1500 Q&A
2003 Chevrolet Suburban 1500 Question: Check engine light with codes 171 & 172.Shop said manifold gasket?
both lean codes,did they ck mass air flow sensor? could be intake leak,always use updated intake gasket from dealer - globalhelper
Agree with greg, does it misfire when first started cold, then smooth out after a few seconds, also indicative of an intake gasket leak! - pushrod
P0171 is a lean code and P0172 is a rich code. It could be the MAF sensor, but it sounds like it is air leaks. Grab a can of carb cleaner and spray along the edges of the intake manifold. See if the idle fluxuates or stumbles. Also listen to the engine when the vehicle starts up cold and see if you hear any exhaust leaks. An exhaust leak before the O2 sensor will cause problems as well. Try switching sides with the O2 sensors before the cat convertors and see if code(s) P0174 or P0175 set. You may just have a bad O2 sensor. If the code changes whent he sensor is moved, replace the sensor. - ChevyASE