Safety Warning
DIY auto repair can cause serious injury, fire, or vehicle damage. These guides are for informational purposes only. Always follow OEM torque specs, wear PPE, and consult a certified mechanic if you are unsure. You are solely responsible for your safety.
1998 Oldsmobile RegencyFACTORY OEM SERVICE PROCEDURE
Engine Control Systems Tests W/Codes
- Introduction
- Self-Diagnostic System
- Diagnostic System
- Diagnostic Procedure
- Powertrain On-Board Diagnostic (OBD) System Check
- Mil Inoperative
- DLC Diagnosis Or No Scan Tool Data
- Reading Trouble Codes
- Trouble Code Definitions
- Hard Or Intermittent Trouble Code Determination
- Clearing Diagnostic Trouble Codes (DTC)
- ECM/Pcm/VCM Location
- Diagnostic Materials
- Special Tools (Diagnostic)
- Scan Tool Usage
- Summary
- Diagnostic Trouble Codes
- Notes
- DTC P0101 - MAF Sensor System Performance
- DTC P0102 - MAF Sensor Circuit Low Frequency
- DTC P0103 - MAF Sensor Circuit High Frequency
- DTC P0107 - Map Sensor Circuit Low Voltage
- DTC P0108 - Map Sensor Circuit High Voltage
- IAT Temperature-To-Resistance Values
- DTC P0112 - IAT Sensor Circuit Low Voltage
- DTC P0113 - IAT Sensor Circuit High Voltage
- ECT Temperature-To-Resistance Values
- DTC P0117 - ECT Sensor Circuit Low Voltage
- DTC P0118 - ECT Sensor Circuit High Voltage
- DTC P0121 - TP Sensor System Performance
- DTC P0122 - TP Sensor Circuit Low Voltage
- DTC P0123 - TP Sensor Circuit High Voltage
- DTC P0125 - ECT Sensor Excessive Time To Reach Closed Loop
- DTC P0131 - Ho2S 1 Circuit Low Voltage
- DTC P0132 - Ho2S 1 Circuit High Voltage
- DTC P0133 - Ho2S 1 Circuit Slow Response
- DTC P0134 - Ho2S 1 Circuit Insufficient Activity
- DTC P0135 - Ho2S 1 Heater Circuit
- DTC P0137 - Ho2S 2 Circuit Voltage Low
- DTC P0138 - Ho2S 2 Circuit Voltage High
- DTC P0140 - Ho2S 2 Insufficient Activity
- DTC P0141 - Ho2S 2 Heater Circuit
- DTC P0171 - Fuel Trim System Lean
- DTC P0172 - Fuel Trim System Rich
- DTC P0201 - Injector No. 1 Control Circuit
- DTC P0202 - Injector No. 2 Control Circuit
- DTC P0203 - Injector No. 3 Control Circuit
- DTC P0204 - Injector No. 4 Control Circuit
- DTC P0205 - Injector No. 5 Control Circuit
- DTC P0206 - Injector No. 6 Control Circuit
- DTC P0230 - Fuel Pump Control Circuit
- DTC P0300-P0306 - Engine Misfire Detected
- DTC P0325 - Knock Sensor Module Circuit
- DTC P0327 - Knock Sensor Circuit Bank 1
- DTC P0332 - Knock Sensor Circuit Bank 2
- DTC P0336 - 18X Reference Signal Circuit
- DTC P0341 - Camshaft Position Sensor Circuit Performance
- DTC P0401 - EGR System Insufficient Flow
- DTC P0403 - EGR Solenoid Control Circuit
- DTC P0404 - EGR Valve Pintle Stuck Closed
- DTC P0405 - EGR Pintle Position Sensor Circuit Low Voltage
- DTC P0420 - TWC System Low Efficiency
- DTC P0440 - EVAP System
- DTC P0442 - EVAP System (Small Leak Detected)
- DTC P0446 - EVAP System Canister Vent Blocked
- DTC P0452 - Fuel Tank Pressure Sensor Low Voltage
- DTC P0453 - Fuel Tank Pressure Sensor High Voltage
- DTC P0506 - IAC System Rpm Low
- DTC P0507 - IAC System Rpm High
- DTC P0530 - A/C Refrigerant Pressure Sensor Circuit
- DTC P0560 - System Voltage
- DTC P0601 - Pcm Memory
- DTC P0602 - Pcm Not Programmed
- DTC P0705 - Transaxle Range Switch Circuit
- DTC P0706 - Transaxle Range System Performance
- DTC P1106 - Map Sensor Circuit Intermittent High Voltage
- DTC P1107 - Map Sensor Circuit Intermittent Low Voltage
- DTC P1111 - IAT Sensor Circuit Intermittent High Voltage
- DTC P1112 - IAT Sensor Circuit Intermittent Low Voltage
- DTC P1114 - ECT Sensor Circuit Intermittent Low Voltage
- DTC P1115 - ECT Sensor Circuit Intermittent High Voltage
- DTC P1121 - TP Sensor Circuit Intermittent High Voltage
- DTC P1122 - TP Sensor Circuit Intermittent Low Voltage
- DTC P1133 - Ho2S Insufficient Switching Sensor 1
- DTC P1134 - Ho2S Transition Time Ratio Sensor 1
- DTC P1257 - Supercharger System OVERBOOST
- DTC P1351 - Ignition Control (Ic) Circuit Open
- DTC P1352 - By-Pass Circuit Open
- DTC P1361 - Ignition Control (Ic) Circuit Not Toggling
- DTC P1362 - By-Pass Circuit Shorted
- DTC P1374 - 3X Reference Circuit
- DTC P1380 - EBTCM DTC Detected Rough Road Data Unusable
- DTC P1381 - Misfire Detected No EBCM/Pcm Serial Data
- DTC P1404 - EGR Valve Pintle Stuck Open
- DTC P1441 - EVAP Emissions System Flow During Non-Purge
- DTC P1554 - Cruise Control Status Circuit
- DTC P1571 - Traction Control System Desired Torque Circuit
- DTC P1573 - EBTCM/Pcm Serial Data Circuit
- DTC P1619 - Engine Oil Life Monitor Reset Circuit
- DTC P1626 - Theft Deterrent System Fuel Enable Circuit
- DTC P1629 - Theft Deterrent Crank Signal Malfunction
- DTC P1635 - 5 Volt-Reference "A" Circuit
- DTC P1639 - 5-Volt Reference "B" Circuit
- DTC P1641 - A/C Relay Control Circuit
- DTC P1646 - Boost Control Solenoid Control Circuit
- DTC P1651 - Fan 1 Relay Control Circuit
- DTC P1652 - Fan 2 Relay Control Circuit
- DTC P1662 - Cruise Control Inhibit Circuit
- DTC P1665 - EVAP Vent Solenoid Control Circuit
- DTC P1667 - Fuel Pump PWM Control Circuit
- DTC P1671 - Mil Control Circuit
- DTC P1673 - Engine Hot Light Control Circuit
- DTC P1676 - EVAP Canister Purge Solenoid Valve Control Circuit
Factory Service Tools
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When to See a Mechanic
Stop DIY work and contact a certified mechanic immediately if any of the following apply:
- • You smell fuel, burning insulation, or see smoke.
- • Brakes feel soft, pull hard to one side, or make grinding noises.
- • The engine overheats, stalls repeatedly, or misfires under load.
- • You are missing required tools, torque specs, or safe lifting equipment.
- • You are not confident in the next step or safety outcome.
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