Why would a 98 ford contour have the fail codes p1121 manufacturer code p1151 manufacturer code p0171 system too lean bank 1 p0174 system too lean bank 2?

Answer 1

P1121 - Throttle Position (TP) Sensor : Inconsistent with MAF Possible causes: 1)Damaged MAF sensor 2)TP sensor not seated properly 3)Damaged TP sensor 4) Air leak between MAF sensor and throttle body Try checking connections to the MAF and TPS sensor. Also remove MAF sensor (you may need security torx bit) and inside you will see 2 wires - VERY gently clean them with a q-tip (BE GENTLE) dipped in electrical cleaner (you will see tons of gunk and black soot come off) and reinstall. P1151 - Lack of HO2S indicates Lean -21 Switch, HEGO Sensor (really fancy name for the Oxygen sensor - of which there are 2) Possible Causes: Electrical * Short to VPWR in harness or HO2S * Water in harness connector * Open/Shorted HO2S circuit * Corrosion or poor mating terminals and wiring * Damaged HO2S * Damaged PCM Fuel System: * Excessive fuel pressure * Leaking/contaminated fuel injectors * Leaking fuel pressure regulator * Low fuel pressure or running out of fuel * Vapor recovery system Induction System: * Air leaks after the MAF * Vacuum Leaks * PCV system Improperly seated engine oil dipstick EGR System: * Leaking gasket * Stuck EGR valve * Leaking diaphragm or EVR Base Engine: * Oil overfill * Cam timing * Cylinder compression * Exhaust leaks before or near the HO2S(s) P071 and P074 - o2 sensors. You most likely have a combination of needing your 02 sensors replaced and needing MAF sensor cleaned/replaced. Also possible vaccum leak.