P1152

P1152 is the Bank 2 Sensor 1 mirror of P1132 — driver-side upstream O2 reading persistently rich without enough switching activity. As with P1132, the rich variant is much rarer than the lean variant on Ford Modular engines. Cheapest-first ladder: confirm LTFT Bank 2 at negative-10 percent or worse to rule out a stuck-rich sensor reading; spec is plus or minus 8 percent at idle. Pull the Bank 2 upstream connector and inspect for oil contamination from a leaking driver-side valve cover gasket — oil on the sensor element makes it read falsely rich. Check fuel pressure at the rail Schrader — 35 to 45 psi spec on 2V Modulars, 55 to 65 psi on 3V returnless; over-spec pressure floods both banks but Bank 2 may set first if a single injector on the driver bank is leaking. Pull injectors 5 through 8 (driver bank on most Modulars) and bench-test pop pressure and spray pattern. The expensive misdiagnosis is replacing the driver-bank cat or the O2 sensor when the actual fault is a $40 leaking injector or a $35 fuel pressure regulator.

Vehicle-specific patterns: 1999-2003 Ford F-150 5.4L 2V trucks suffer fuel pressure regulator failure dumping fuel into the upper intake — pull the regulator vacuum reference hose, smell for gas. 2001-2004 Ford Mustang GT 4.6L 2V cars with high mileage develop sticky injectors from sitting; Lucas or Techron through the rail at 90 psi cleans most of them. 2005-2010 Ford Expedition 5.4L 3V suffers driver-side VCT phaser failure that holds the cam advanced and skews the Bank 2 fuel trim rich — TSB 14-0194 covers the phaser replacement. 2003-2007 Ford E-Series 5.4L 2V vans suffer crank-position-induced rich misfire on the driver bank when the timing chain tensioner wears. Estimated repair: $40 to $1,600.