I want to find out if one of my O2 sensors are bad is there a way to test them? My check engine light is not on but I know that GM computers only put out the light when the sensor fails completley.

Well lets explain a few things to you first off.

"GM computer only put out the light when the sensor fails completley".

WRONG! Where did you hear that from?

If the PCM sees the sensor switching from rich to lean say four times a second, but then it starts doing it two times a second, it will set a trouble code, for slow response O2 sensor. GM doesnt have a choice it is called federal regulation all manufactures MUST follow the SAME regulations regarding emissions control.

Your source for your info is a moron, no offense.

You cant test an O2 sensor, you dont need to, if it goes bad or begins to your computer will let you know right away.

CEL = O2 sensor and everything else is working how is should

anything else?




- 2004 Cavalier - 124k, owned since new

well someone posted that on the forum, I have checked my service manual that I got yesterday you need the computer to test the O2 sensor. I would like to know if my O2 sensor could be bad because the car has 55k on it.

could be, who knows

i have a CEL for slow response right now, unless it starts affecting how the car is running i won't be changing it for a week or 2. as it stands last few tanks i have been getting 30.3 to 31.8 MPG and may try going to mid grade for a few tanks and see if it makes a difference worth the increase in cost.

Rob S wrote:
Your source for your info is a moron, no offense.

You cant test an O2 sensor, you dont need to, if it goes bad or begins to your computer will let you know right away.



anything else?

Well, your source for that info is a moron. Every time the ECU starts up, it spends some time testing the O2 sensors. These tests can be initiated through an appropriate scan tool. Rich/lean switch time is not the only sign of a bad sensor. Some sensors may switch at the correct speed, but not provide the correct voltages. This will not throw a CEL, but the car will run oddly. Bad gas mileage is a sign of this. Its easy to replicate, simply dip your O2 sensor element in some water then let it dry. Or run race gas or leaded fuel.





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Shifted wrote:

Rob S wrote:
Your source for your info is a moron, no offense.

You cant test an O2 sensor, you dont need to, if it goes bad or begins to your computer will let you know right away.



anything else?

Well, your source for that info is a moron. Every time the ECU starts up, it spends some time testing the O2 sensors. These tests can be initiated through an appropriate scan tool. Rich/lean switch time is not the only sign of a bad sensor. Some sensors may switch at the correct speed, but not provide the correct voltages. This will not throw a CEL, but the car will run oddly. Bad gas mileage is a sign of this. Its easy to replicate, simply dip your O2 sensor element in some water then let it dry. Or run race gas or leaded fuel.

Thats a bunch of bull@!#$. The computer also monitors voltage, if the voltage goes to high above or to far below a calibrated limit, the CEL will go on.




- 2004 Cavalier - 124k, owned since new

Sorry, not true. The computer does not monitor voltage. Only lean/rich switch time. Obviously if it has way too high of a signal, or way too low of a signal, it will throw a CEL, but how is it supposed to know if .485v is correct or not? Water and lead damage the sensor, but the switching time is a separate function.

I've spent a LOT of time studying this stuff, I have to, because I'm writing software to edit the ECU's. I know a LOT about how they work, and how the sensors work.





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what codes do you have for the cel to come on....

DTC Title
P0030 HO2S Heater Circuit Bank 1 Sensor 1
P0030 HO2S Heater Control Circuit Bank 1 Sensor 1
P0030 HO2S Heater Control Circuit Sensor 1
P0031 HO2S Heater Circuit Low Voltage Bank 1 Sensor 1
P0031 "HO2S Heater Control Circuit Low (bank 1, sensor 1)"
P0031 O2 Sensor 1/1 Heater Ckt Low
P0032 HO2S Heater Circuit High Voltage Bank 1 Sensor 1
P0032 "HO2S Heater Control Circuit High (bank 1, sensor 1)"
P0032 O2 Sensor 1/1 Heater Ckt High
P0036 HO2S Heater Circuit Bank 1 Sensor 2
P0036 HO2S Heater Control Circuit Bank 1 Sensor 2
P0036 HO2S Heater Control Circuit Sensor 2
P0037 HO2S Heater Circuit Low Voltage Bank 1 Sensor 2
P0037 HO2S Heater Control Circuit Low
P0037 "HO2S Heater Control Circuit Low (bank 1, sensor 2)"
P0037 O2 Sensor 1/2 Heater Ckt Low
P0038 HO2S Heater Circuit High Voltage Bank 1 Sensor 2
P0038 HO2S Heater Control Circuit High
P0038 "HO2S Heater Control Circuit High (bank 1, sensor 2)"
P0038 O2 Sensor 1/2 Heater Ckt High
P0043 "HO2S Heater Control Circuit Low (bank 1, sensor 3)"
P0043 O2 Sensor 1/3 Heater Ckt Low
P0044 "HO2S Heater Control Circuit High (bank 1, sensor 3)"
P0044 O2 Sensor 1/3 Heater Ckt High
P0050 HO2S Heater Circuit Bank 2 Sensor 1
P0051 HO2S Heater Circuit Low Voltage Bank 2 Sensor 1
P0051 "HO2S Heater Control Circuit Low (bank 2, sensor 1)"
P0051 O2 Sensor 2/1 Heater Ckt Low
P0052 HO2S Heater Circuit High Voltage Bank 2 Sensor 1
P0052 "HO2S Heater Control Circuit High (bank 2, sensor 1)"
P0052 O2 Sensor 2/1 Heater Ckt High
P0056 HO2S Heater Circuit Bank 2 Sensor 2
P0057 HO2S Heater Circuit Low Voltage Bank 2 Sensor 2
P0057 "HO2S Heater Control Circuit Low (bank 2, sensor 2)"
P0057 O2 Sensor 2/2 Heater Ckt Low
P0058 HO2S Heater Circuit High Voltage Bank 2 Sensor 2
P0058 "HO2S Heater Control Circuit High (bank 2, sensor 2)"
P0058 O2 Sensor 2/2 Heater Ckt High
P0130 Closed Loop Test; O2 Sensor Subsystem
P0130 HO2S Circuit Bank 1 Sensor 1
P0130 HO2S Circuit Closed Loop (CL) Performance Sensor 1
P0130 HO2S Circuit Sensor 1
P0130 O2 Sensor 1/1 Heater Relay Ckt
P0130 O2S Circuit Closed Loop [CL] Performance Sensor 1
P0130 O2S Circuit Sensor 1
P0130 O2S Closed Loop Rationality
P0131 (Alt. Fuel) HO2S Circuit Low Voltage Bank 1 Sensor 1
P0131 HO2S Circuit Bank 1 Sensor 1 Low Voltage
P0131 HO2S Circuit Low Voltage Bank 1 Sensor 1
P0131 HO2S Circuit Low Voltage Bank 1 Sensor 1
P0131 HO2S Circuit Low Voltage Sensor 1
P0131 Low Voltage; O2 Sensor Subsystem
P0131 O2 Sensor 1/1 Voltage Low
P0131 O2 SENSOR SUBSYSTEM - LOW VOLTAGE
P0131 O2 Sensor Subsystem Low Voltage
P0131 O2S Circuit Low Voltage Sensor 1
P0132 (Alt. Fuel) HO2S Circuit High Voltage Bank 1 Sensor 1
P0132 High Voltage; O2 Sensor Subsystem
P0132 HO2S Circuit Bank 1 Sensor 1 High Voltage
P0132 HO2S Circuit High Voltage Bank 1 Sensor 1
P0132 HO2S Circuit High Voltage Sensor 1
P0132 O2 Sensor 1/1 Voltage High
P0132 O2 SENSOR SUBSYSTEM - HIGH VOLTAGE
P0132 O2 Sensor Subsystem High Voltage
P0132 O2S Circuit High Voltage Sensor 1
P0133 HO2S Circuit Bank 1 Sensor 1 Slow Response
P0133 HO2S Slow Response Bank 1 Sensor 1
P0133 HO2S Slow Response Sensor 1
P0133 O2 Sensor 1/1 Slow Response
P0133 O2 SENSOR SUBSYSTEM - SLOW RESPONSE
P0133 O2 Sensor Subsystem Slow Response
P0133 O2S Slow Response Sensor 1
P0133 Slow Response; O2 Sensor Subsystem
P0134 (Alt. Fuel) HO2S Circuit Insufficient Activity Bank 1 Sensor 1
P0134 HO2S Circuit Bank 1 Sensor 1 No Activity
P0134 HO2S Circuit Insuff. Activity Bank 1 Sensor 1
P0134 HO2S Circuit Insuff. Activity Sensor 1
P0134 HO2S Circuit Insufficient Activity Bank 1 Sensor
P0134 HO2S Circuit Insufficient Activity Bank 1 Sensor 1
P0134 HO2S Circuit Insufficient Activity Sensor 1
P0134 O2 Sensor 1/1 Signal Inactive
P0134 O2S Circuit Insufficient Activity Sensor 1
P0135 (Alt. Fuel) HO2S Heater Circuit Bank 1 Sensor 1
P0135 HO2S Heater Circuit Bank 1 Sensor 1
P0135 HO2S Heater Circuit Performance Bank 1 Sensor 1
P0135 HO2S Heater Circuit Sensor 1
P0135 HO2S Heater Ckt. Bank 1 Sensor 1
P0135 HO2S Heater Ckt. Sensor 1
P0135 HO2S Heater Control Circuit Sensor 1
P0135 HO2S Heater Performance Bank 1 Sensor 1
P0135 HO2S Heater Performance Sensor 1
P0135 O2 Sensor 1/1 Heater Performance
P0136 HO2S Circuit Bank 1 Sensor 2
P0136 HO2S Circuit Sensor 2
P0136 O2 Sensor 1/2 Heater Relay Ckt
P0137 HEATED O2 SENSOR - LOW VOLTAGE
P0137 Heated O2 Sensor (Rear) Low Voltage
P0137 HO2S Circuit Bank 1 Sensor 2 Low Voltage
P0137 HO2S Circuit Low Voltage Bank 1 Sensor 2
P0137 HO2S Circuit Low Voltage Sensor 2
P0137 O2 Sensor 1/2 Voltage Low
P0138 Heated O2 Sensor (Rear) High Voltage
P0138 HEATED O2 SENSOR -HIGH VOLTAGE
P0138 HO2S Circuit Bank 1 Sensor 2 High Voltage
P0138 HO2S Circuit High Voltage Bank 1 Sensor 2
P0138 HO2S Circuit High Voltage Sensor 2
P0138 O2 Sensor 1/2 Voltage High
P0139 HO2S Circuit Bank 1 Sensor 2 Slow Response
P0139 HO2S Slow Response Bank 1 Sensor 2
P0139 O2 Sensor 1/2 Slow Response
P0140 HO2S Circuit Bank 1 Sensor 2 No Activity
P0140 HO2S Circuit Insuff. Activity Bank 1 Sensor 2
P0140 HO2S Circuit Insuff. Activity Sensor 2
P0140 HO2S Circuit Insufficient Activity Bank 1 Sensor
P0140 HO2S Circuit Insufficient Activity Bank 1 Sensor 2
P0140 HO2S Circuit Insufficient Activity Sensor 2
P0140 O2 Sensor 1/2 Signal Inactive
P0141 HO2S Heater Circuit Bank 1 Sensor 2
P0141 HO2S Heater Circuit Performance Bank 1 Sensor 2
P0141 HO2S Heater Circuit Sensor 2
P0141 HO2S Heater Ckt. Bank 1 Sensor 2
P0141 HO2S Heater Control Circuit Sensor 2
P0141 HO2S Heater Performance Bank 1 Sensor 2
P0141 HO2S Heater Performance Sensor 2
P0141 O2 Sensor 1/2 Heater Performance
P0142 HO2S Circuit Bank 1 Sensor 3
P0143 HO2S Circuit Bank 1 Sensor 3 Low Voltage
P0143 HO2S Circuit Low Voltage Bank 1 Sensor 3
P0143 O2 Sensor 1/3 Voltage Low
P0144 HO2S Circuit Bank 1 Sensor 3 High Voltage
P0144 HO2S Circuit High Voltage Bank 1 Sensor 3
P0144 O2 Sensor 1/3 Voltage High
P0145 HO2S Circuit Bank 1 Sensor 2 Slow Response
P0145 O2 Sensor 1/3 Slow Response
P0146 HO2S Circuit Bank 1 Sensor 3 No Activity
P0146 HO2S Circuit Insuff. Activity Bank 1 Sensor 3
P0146 HO2S Circuit Insufficient Activity Bank 1 Sensor 3
P0146 O2 Sensor 1/3 Signal Inactive
P0147 HO2S Heater Circuit Bank 1 Sensor 3
P0147 HO2S Heater Ckt. Bank 1 Sensor 3
P0147 HO2S Heater Performance Bank 1 Sensor 3
P0147 O2 Sensor 1/3 Heater Performance
P0150 HO2S Circuit Bank 2 Sensor 1
P0151 (Alt. Fuel) HO2S Circuit Low Voltage Bank 2 Sensor 1
P0151 HO2S Circuit Bank 2 Sensor 1 Low Voltage
P0151 HO2S Circuit Low Voltage Bank 2 Sensor 1
P0151 O2 Sensor 2/1 Voltage Low
P0152 (Alt. Fuel) HO2S Circuit High Voltage Bank 2 Sensor 1
P0152 HO2S Circuit Bank 2 Sensor 1 High Voltage
P0152 HO2S Circuit High Voltage Bank 2 Sensor 1
P0152 O2 Sensor 2/1 Voltage High
P0153 HO2S Circuit Bank 2 Sensor 1 Slow Response
P0153 HO2S Slow Response Bank 2 Sensor 1
P0153 O2 Sensor 2/1 Slow Response
P0154 (Alt. Fuel) HO2S Circuit Insufficient Activity Bank 2 Sensor 1
P0154 HO2S Circuit Bank 2 Sensor 1 No Activity
P0154 HO2S Circuit Insuff. Activity Bank 2 Sensor 1
P0154 HO2S Circuit Insufficient Activity Bank 2 Sensor
P0154 HO2S Circuit Insufficient Activity Bank 2 Sensor 1
P0154 O2 Sensor 2/1 Signal Inactive
P0155 (Alt. Fuel) HO2S Heater Circuit Bank 2 Sensor 1
P0155 HO2S Heater Circuit Bank 2 Sensor 1
P0155 HO2S Heater Circuit Performance Bank 2 Sensor 1
P0155 HO2S Heater Ckt. Bank 2 Sensor 1
P0155 HO2S Heater Performance Bank 2 Sensor 1
P0155 O2 Sensor 2/1 Heater Performance
P0156 HO2S Circuit Bank 2 Sensor 2
P0157 HO2S Circuit Bank 2 Sensor 2 Low Voltage
P0157 HO2S Circuit Low Voltage Bank 2 Sensor 2
P0157 O2 Sensor 2/2 Voltage Low
P0158 HO2S Circuit Bank 2 Sensor 2 High Voltage
P0158 HO2S Circuit High Voltage Bank 2 Sensor 2
P0158 O2 Sensor 2/2 Voltage High
P0159 HO2S Circuit Bank 2 Sensor 2 Slow Response
P0159 HO2S Slow Response Bank 2 Sensor 2
P0159 O2 Sensor 2/2 Slow Response
P0160 HO2S Circuit Bank 2 Sensor 2 No Activity
P0160 HO2S Circuit Insuff. Activity Bank 2 Sensor 2
P0160 HO2S Circuit Insufficient Activity Bank 2 Sensor
P0160 HO2S Circuit Insufficient Activity Bank 2 Sensor 2
P0160 O2 Sensor 2/2 Signal Inactive
P0161 HO2S Heater Circuit Bank 2 Sensor 2
P0161 HO2S Heater Circuit Performance Bank 2 Sensor 2
P0161 HO2S Heater Ckt. Bank 2 Sensor 2
P0161 HO2S Heater Performance Bank 2 Sensor 2
P0161 O2 Sensor 2/2 Heater Performance
P0162 HO2S Circuit Bank 2 Sensor 3
P0163 HO2S Circuit Bank 2 Sensor 3 Low Voltage
P0164 HO2S Circuit Bank 2 Sensor 3 High Voltage
P0165 HO2S Circuit Bank 2 Sensor 3 Slow Response
P0166 HO2S Circuit Bank 2 Sensor 3 No Activity
P0166 HO2S Circuit Bank 2 Sensor 3 No Activity Detected
P0167 HO2S Heater Circuit Bank 2 Sensor 3
P0167 HO2S Heater Ckt. Bank 2 Sensor 3
P1031 HO2S Heater Current Monitor Control Circuit Sensors 1
P1032 HO2S Heater Warm Up Control Circuit Sensors 1
P1127 "Exhaust Not Warm, Downstream O2 Sensor Not Tested"
P1128 Upstream HO2S Sensors Swapped
P1129 Downstream HO2S Sensors Swapped
P1130 HO2S Circuit Low Variance Bank 1 Sensor 1
P1130 Lack Of HO2S11 Switches - Fuel Trim At Limit
P1131 HO2S Circuit Low Variance Bank 1 Sensor 2
P1131 Lack Of HO2S11 Switches - Sensor Indicates Lean
P1132 HO2S Circuit Low Variance Bank 2 Sensor 1
P1132 Lack Of HO2S11 Switches - Sensor Indicates Rich
P1133 """HO2S Cross Counts Bank 1 Sensor 1 Too Fewisp1""""&__trat"""
P1133 HO2S Bn1 Sen. 1 Insufficient Switching
P1133 HO2S Cross Counts Bank 1 Sensor 1 Too Few
P1133 HO2S Insuff. Switching Bank 1 Sensor 1
P1133 HO2S Insuff. Switching Bank 1 Sensor1
P1133 HO2S Insuff. Switching Sensor 1
P1133 HO2S Insufficient Switching Bank 1 Sensor 1
P1133 HO2S Insufficient Switching Sensor 1
P1133 O2 SENSOR SUBSYSTEM - SWITCHING PROBLEM
P1133 O2 Sensor Subsystem Two Few Switches
P1133 O2S Cross Counts Bank 1 Sensor 1 Too Few
P1133 O2S Insufficient Switching Sensor 1
P1133 Two Few Switches; O2 Sensor Subsystem
P1134 HO2S Bank 1 Sen. 1 Transition Time Ratio
P1134 HO2S Bn1 Sen. 1 Transition Time Ratio
P1134 HO2S Transition Time Ratio Bank1 Sensor 1
P1134 HO2S Transition Time Ratio Bank 1 Sensor 1
P1134 HO2S Transition Time Ratio Bank1 Sensor 1
P1134 HO2S Transition Time Ratio Sensor 1
P1134 O2 SENSOR SUBSYSTEM - TRANSITION SWITCH TIME
P1134 O2 Sensor Subsystem Rich/Lean Lean/Rich Ratio Error
P1134 O2S Transition Time Ratio Sensor 1
P1134 Rich/Lean Lean/Rich Ratio Error; O2 Sensor Subsystem
P1135 HO2S Bank 1 Sen. 1 Mean Voltage Level Lean
P1135 HO2S Bn1 Sen. 1 Mean Volts Level Lean
P1135 HO2S Lean Mean Bank 1 Sensor 1
P1135 HO2S11 Heater Circuit Low
P1136 HO2S Bank 1 Sen. 1 Mean Voltage Level Rich
P1136 HO2S Bn1 Sen. 1 Mean Volts Level Rich
P1136 HO2S Rich Mean Bank 1 Sensor 1
P1136 HO2S11 Heater Circuit High
P1137 HO2S Bank 1 Sensor 2 Lean System or Low Voltage
P1137 Lack Of HO2S12 Switches - Sensor Indicates Lean
P1137 O2S Bank 1 Sensor 2 Lean System or Low Voltage
P1138 HO2S Bank 1 Sensor 2 Rich or High Voltage
P1138 Lack Of HO2S12 Switches - Sensor Indicates Rich
P1138 O2S Bank 1 Sensor 2 Rich or High Voltage
P1139 HO2S Cross Counts Bank 1 Sensor 2
P1139 HO2S Insuff. Switching Bank 1 Sensor 2
P1139 HO2S Insuff. Switching Bank 1 Sensor2
P1139 HO2S Insufficient Switching Bank 1 Sensor 2
P1140 HO2S Transition Time Ratio Bank 1 Sensor 2
P1141 HO2S Bank 1 Sensor 2 Mean Voltage Level
P1141 HO2S Heater Circuit Bank 1 Sensor 2
P1141 HO2S Heater Power Stage Circuit Bank 1 Sensor 2
P1141 HO2S12 Heater Circuit Low
P1142 HO2S12 Heater Circuit High
P1143 HO2S Bank 1 Sensor 3 Lean System or Low Voltage
P1143 "Lack of HO2S Switches, HO2S13 Indicates Lean"
P1144 HO2S Bank 1 Sensor 3 Rich or High Voltage
P1144 "Lack of HO2S Switches, HO2S13 Indicates Rich"
P1145 HO2S Cross Counts Bank 1 Sensor 3
P1150 Lack Of HO2S21 Switches - Fuel Trim At Limit
P1151 Lack Of HO2S21 Switches - Sensor Indicates Lean
P1152 Lack Of HO2S21 Switches - Sensor Indicates Rich
P1153 """HO2S Cross Counts Bank 2 Sensor 1 Too Fewisp1""""&__trat"""
P1153 HO2S Bn2 Sen. 1 Insufficient Switching
P1153 HO2S Insuff. Switching Bank 2 Sensor 1
P1153 HO2S Insuff. Switching Bank 2 Sensor1
P1153 HO2S Insufficient Switching Bank 2 Sensor 1
P1154 HO2S Bank 2 Sen. 1 Transition Time Ratio
P1154 HO2S Bn2 Sen. 1 Transition Time Ratio
P1154 HO2S Transition Time Ratio Bank 2 Sensor 1
P1155 HO2S Bank 2 Sen. 1 Mean Voltage Level Lean
P1155 HO2S Bn2 Sen. 1 Mean Volts Level Lean
P1155 HO2S Lean Mean Bank 2 Sensor 1
P1156 HO2S Bank 2 Sen. 1 Mean Voltage Level Rich
P1156 HO2S Bn2 Sen. 1 Mean Volts Level Rich
P1156 HO2S Rich Mean Bank 2 Sensor 1
P1157 HO2S Bank 2 Sensor 2 Lean System or Low Voltage
P1157 Lack Of HO2S22 Switches - Sensor Indicates Lean
P1158 HO2S Bank 2 Sensor 2 Rich or High Voltage
P1158 Lack Of HO2S22 Switches - Sensor Indicates Rich
P1159 HO2S Cross Counts Bank 2 Sensor 2
P1161 HO2S Heater Control Circuit Bank 2 Sensor 2
P1161 HO2S Heater Power Stage Circuit Bank 2 Sensor 2
P1163 HO2S Bank 2 Sensor 3 Lean System or Low Voltage
P1164 HO2S Bank 2 Sensor 3 Rich or High Voltage
P1165 HO2S Cross Counts Bank 2 Sensor 3
P1169 Feedback A/F Mixture Control (HO2S12)
P1170 Feedback A/F Mixture Control (HO2S11)
P1173 Feedback A/F Mixture Control (HO2S21)
P1174 System Too Lean - Banks 1 and 2 (Suspect HO2S)
P1175 System Too Rich - Banks 1 and 2 (Suspect HO2S)
P1185 O2 Sensor Heater Circuit Open - Hardware Fault
P1186 O2 Sensor Heater Circuit Shorted - Hardware Fault
P1187 O2 Sensor Heater Circuit Open - Inferred Fault
P1188 O2 Sensor Heater Circuit Resistance
P1189 O2 Sensor Heater Circuit Low Resistance Fault 1
P1190 O2 Sensor Heater Circuit Low Resistance Fault 2
P1191 O2 Sensor Heater Circuit Open - Hardware Fault
P1192 O2 Sensor Heater Circuit Shorted
P1193 O2 Sensor Heater Circuit Open - Inferred Fault
P1194 O2 Sensor Heater Circuit Resistance Fault
P1194 PWM O2 Heater Performance
P1195 Catalyst Monitor Slow O2 Sensor 1/1
P1195 O2 Sensor Heater Circuit Low Resistance Fault 1
P1196 Catalyst Monitor Slow O2 Sensor 2/1
P1196 O2 Sensor Heater Circuit Low Resistance Fault 2
P1197 Catalyst Monitor Slow O2 Sensor 1/2
P1646 Linear O2 Sensor Control Chip (Bank 1)
P1647 Linear O2 Sensor Control Chip (Bank 2)






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will these codes be stored on the computer eventhough my CEL isn't on?

Yes.





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There really is no effective way to test an oxygen sensor. They generally require temperatures of over 300c to begin working properly. I've read postings of people caiming to test them by using a torch, but yeah, I don't know about that.


------------------------------------------------------------------------------------------------------------------------------------------

John Leahy
'01 Cavalier Z24 - 5Speed

MaxThrottle.Com

Shifted:

If I bought a scanner to check the OBD 2 codes and found out whats wrong with my car, it would work as if I had a CEL on? I'm having a problem where my fuel economy is only 19-20 mpg city and the exhaust pipe is sooty (black stuff). I think its most likley my 02 sensor but the scanner should tell me which one.

The only one that controls your fuel is the first one. The sensor is cheap ($25), so replace it and see if it helps. People will tell you that the second sensor tries to control the long term fuel trim, but thats completely false. The first sensor controls the short term fuel trim. Long term fuel trim adjustments are based on the short term fuel trims.

I replaced my sensor and gas mileage was significantly improved. But I had no CEL's or codes stored in memory.





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thanks alot man you really know your stuff

BTW shifted what did you take in college/university? is this car programming stuff your career?

Its not my career, its a side business. I started off in college studying software engineering, but switched to Management of Information Systems in my Junior year. My career is going to change shortly, I'll be installing and programming control systems on oil rigs, cargo ships, and government contracts (destroyers, tenders, mine sweepers,etc).





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so heres the plan now, I'm gonna head to crappy tire (no autozones here in Canada) and buy the scanner for 250$ scan the codes and return it or I might call up Partsource if I can borrow one, thats if its an option . This will give a straight answer as to what is wrong with my car. I will also change the spark plugs because they are worn out, the gaps are all out of factory specs and I don't see the option of fooling around with gapping them if i can buy them for 3$. The only problem is the o2 sensor cost, 25$ seems to be a fair price in the states but over here parts are expensive, i want a Delco and theres only a few places that sell them, i'm gonna call around to see the prices.

Just got a P1137 code of my own, and have been getting crappy gas mileage and a rough ride since he S/C install. I really just wanted to post on this thread to push it to the top for anyone who may be looking for engine code descriptions.....this thread has them all looks like, could be sticy material. Anyhow Thanks!