Front UEGO Slow/Delayed Response Monitor (2010 My+)
The front UEGO monitor also detects malfunctions on the UEGO sensor such as reduced response or delayed response that would cause vehicle emissions to exceed 1.5x the standard (2.5x the standard for PZEV). The response rate is evaluated by entering a special 0.5 Hz square wave, fuel control routine. This routine drives the air/fuel ratio around stoichiometry at a calibratable frequency and magnitude, producing predictable oxygen sensor signal amplitude.
A UEGO slow or delayed sensor will show an increased response time which is compared to a no-fault polygon. Combinations of the rich to lean and lean to rich response times that fall outside the polygon indicate a sensor malfunction (P0133 Bank 1, P0153 Bank 2).
UEGO "RESPONSE RATE" OPERATION
| DTCs | P0133 - O2 Sensor Circuit Slow/Delayed Response Bank 1, P0153 - O2 Sensor Circuit Slow/Delayed Response Bank 2 |
| Monitor execution | once per driving cycle |
| Monitor Sequence | > 30 seconds time in lack of movement test, > 30 seconds time in lack of switch test |
| Sensors OK | ECT, IAT, MAF, MAP, VSS, TP, ETC, FRP, FVR, DPFE EGR, VCT, VMV/EVMV, CVS, CPV, EVAPSV, FTP, CKP, CMP, ignition coils, injectors, no misfire DTCs, no system failures affecting fuel, no EVAP gross leak failure, UEGO heaters OK, no "lack of switching" malfunction, no "lack of movement" malfunction, no UEGO circuit malfunction, no UEGO FAOS monitor malfunction |
| Monitoring Duration | 12 seconds |
TYPICAL UEGO "RESPONSE RATE" ENTRY CONDITIONS
| Entry Condition | Minimum | Maximum |
| Flex Fuel Composition not changing | ||
| Not in Phase 0 of Evap Monitor, Purge intrusive test not running | ||
| No Purge System reset | ||
| Not performing CSER spark retard | ||
| Not performing intrusive UEGO Lack of Movement "defib" | ||
| No IMRC transition in progress before entering the monitor and while in monitor | ||
| Engine Coolant Temp | 150 °F | 240 °F |
| Intake Air Temp | 140 °F | |
| Time since entering closed loop fuel | 10 seconds | |
| Inferred Catalyst Midbed Temperature | 1600 °F | |
| Fuel Level | 15% | |
| Short Term Fuel Trim Range | -5% | 5% |
| Short Term Fuel Trim Absolute Change while in monitor | 15% | |
| Air Mass | 1.2 lbs/min | |
| Engine Load | 20% | 70% |
| Maximum change in engine load while in monitor | 0.25 | |
| Vehicle Speed | 35 mph | 80 mph |
| Maximum change in vehicle speed while in monitor | 9 mph | |
| Engine RPM | 1000 rpm | 3000 rpm |
| Maximum change in engine rpm while in monitor | 150 rpm | |
| Commanded versus actual lambda range while in monitor | 0.85 | 1.15 |
| No excessive cam angle movement over a half cycle A/F modulation when exhaust cam position is >= 40 degree or intake cam position >= -10 degree to indicate an acceptable A/F disturbance due to cam angle movement. | 3 degree | |
| No excessive movement between currently utilized long term fuel trim cells (1 = complete change from one cell to adjacent cell) | 0.5 | |
| UEGO ASIC not in recalibration mode | ||
| No air passing through during valve overlap (scavenging). | ||
| Battery Voltage | 11.0 Volts | 18.0 Volts |
J1979 Front UEGO Mode $06 Data
| Monitor ID | Test ID | Description | Unit |
| $01 | $87 | UEGO11 Rich to Lean Response Time (P0133) | seconds |
| $01 | $88 | UEGO11 Lean to Rich Response Time (P0133) | seconds |
| $05 | $87 | UEGO21 Rich to Lean Response Time (P0153) | seconds |
| $05 | $88 | UEGO21 Lean to Rich Response Time (P0153) | seconds |