99 Blazer code p0121 and p0122

[Nandy]

I have a vague idea of what to do and where to look but if anyone has some good hints got for it. I know I have to check the wiring to be good and the sensor to be installed right (haven't located the sensor yet but I bet it is in the throttle body). Did not have that problem before but I did took the motor apart all the way to the cylinder heads so I might have move/messed/kink something. New gaskets everywhere.

 

[Bob_VT]

Re: 99 Blazer code p0121 and p0122

GM Codes


P0102 Mass Air Flow circuit Low Input.
P0103 Mass Air Flow circuit High Input.
P0106 EGR Barometric Pressure Sensor Input Signal is out of Self-Test Range.
P0107 EGR/BARO Signal circuit is Less Than Self-Test minimum.
P0108 EGR Barometric Pressure Sensor Input Signal is out of Self-Test Range.
P0112 Intake Air Temperature circuit Low Input.
P0113 Intake Air Temperature circuit High Input.
P0117 Engine Coolant Temperature circuit Low Input.
P0118 Engine Coolant Temperature circuit High Input.
P0121 In-Range Operating Throttle Position Sensor circuit failure.
P0122 Throttle Position Sensor circuit Low Input.
P0123 Throttle Position Sensor circuit High Input.
P0125 Insufficient Coolant Temperature to enter Closed Loop.
P0126 Insufficient Coolant Temperature for Stable Operation.
P0131 Upstream Heated Oxygen Sensor circuit out of range - Bank No. 1.
P0132 Upstream Heated Oxygen Sensor circuit Voltage High - Bank No. 1.
P0133 Upstream Heated Oxygen Sensor circuit Slow Response - Bank No. 1.
P0135 Upstream Heated Oxygen Sensor Heater circuit fault - Bank No. 1.
P0136 Downstream Heated Oxygen Sensor circuit fault - Bank No. 1.
P0138 Downstream Heated Oxygen Sensor circuit Voltage High - Bank No. 1.
P0140 Downstream Heated Oxygen Sensor circuit Faulty - Bank No. 1.
P0141 Downstream Heated Oxygen Sensor Heater circuit fault - Bank No. 1.
P0151 Upstream Heated Oxygen Sensor circuit out of range - Bank No. 2.
P0152 Upstream Heated Oxygen Sensor circuit Voltage High - Bank No. 2.
P0153 Upstream Heated Oxygen Sensor circuit Slow Response - Bank No. 2.
P0155 Upstream Heated Oxygen Sensor Heater circuit fault - Bank No. 2.
P0156 Downstream Heated Oxygen Sensor circuit fault - Bank No. 2.
P0158 Downstream Heated Oxygen Sensor circuit Voltage High - Bank No. 2.
P0160 Downstream Heated Oxygen Sensor circuit fault - Bank No. 2.
P0161 Downstream Heated Oxygen Sensor Heater circuit fault - Bank No. 2.
P0171 System Too Lean - Bank No. 1.
P0172 System Too Rich - Bank No. 1.
P0174 System Too Lean - Bank No. 2.
P0175 System Too Rich - Bank No. 2.
P0176 Flexible Fuel Sensor.
P0180 Engine Fuel Temperature Sensor circuit - Electrical fault.
P0181 Engine Fuel Temperature Sensor circuit - Electrical fault.
P0182 Engine Fuel Temperature Sensor circuit - Electrical fault.
P0183 Engine Fuel Temperature Sensor circuit - Electrical fault.
P0187 Engine Fuel Temperature Sensor circuit.
P0188 Engine Fuel Temperature Sensor circuit.
P0190 FRP Sensor Signal Low.
P0191 Engine Fuel Temperature Sensor circuit.
P0192 Engine Fuel Temperature Sensor circuit .
P0193 Engine Fuel Temperature Sensor circuit.
P0222 Throttle Position Sensor B circuit Input Low.
P0223 Throttle Position Sensor B circuit Input High.
P0230 Fuel Pump Primary circuit fault.
P0231 Fuel Pump Secondary circuit Low.
P0232 Fuel Pump Secondary circuit High.
P0300 Random Misfire Detected.
P0301 Misfire Detected - Cylinders 1-10.
P0302 Misfire Detected - Cylinders 1-10.
P0303 Misfire Detected - Cylinders 1-10.
P0304 Misfire Detected - Cylinders 1-10.
P0305 Misfire Detected - Cylinders 1-10.
P0306 Misfire Detected - Cylinders 1-10.
P0307 Misfire Detected - Cylinders 1-10.
P0308 Misfire Detected - Cylinders 1-10.
P0309 Misfire Detected - Cylinders 1-10.
P0310 Misfire Detected - Cylinders 1-10.
P0320 Ignition Engine Speed (PIP) Input circuit fault.
P0325 A Spark Knock Occurred - Sensor Circuitry did not respond.
P0326 Spark Knock has not been sensed.
P0330 A Spark Knock occurred - Sensor Circuitry did not respond.
P0331 Spark Knock has not been sensed.
P0340 Camshaft Position Sensor circuit fault.
P0350 Ignition Coil Primary circuit fault.
P0351 Ignition Coil A Primary circuit fault.
P0352 Ignition Coil

 

[Nandy]

Re: 99 Blazer code p0121 and p0122

Thanks, I know what the codes are. Just trying to get advise on what to do next from those who has seen this trouble before.

 

[TilliamWe]

Re: 99 Blazer code p0121 and p0122

Obviously check the wires. Also, check for any restriction in the air cleaner or tube leading to it. I had a 90 Van with TBI, and it was way down on power one day, and it threw a TPS code. I went to replace the TPS, which included removing the air cleaner and intake tube... A bird had start to build a nest! Cleared the restriction, light went out, truck ran great again, TPS returned!

 

[Nandy]

Re: 99 Blazer code p0121 and p0122

That reminds me... Last night I could step on the gas to rev the motor and if the rev was quick and over 2k rpm most of the time the motor will idle down and die. Never ever had such a problem before. This is my hauling vehicle and has always been strong.

 

[ken_23434]

Re: 99 Blazer code p0121 and p0122

For my motorcycle, truck and cars that I have ever dealt with TPS issues, it normally involves hooking up a voltmeter between 2 of the wires on the sensor and slowing rotating the throttle from shut to full open back to shut. If the TPS is good, you will see a low voltage going to a higher one (probably 5v) and back to the original voltage with no sudden "jumps".

Sometimes, there will be a bad spot in the TPS, where the voltage will suddenly drop to 0 volts and then jump back up.

The other test is basically the same, except you monitor the TPS output using a diagnostic scanner (OBD-II hand held thing) and see what the computer is reading.

If it looks good at the tps using a voltmeter, and bad on the OBD-II scanner, then it is likely a bad connector or wiring between the ECM and the TPS. If you see a bad reading at the sensor (as I described above) then it is the sensor.

 

[DECK SWABBER 58]

Re: 99 Blazer code p0121 and p0122

For my motorcycle, truck and cars that I have ever dealt with TPS issues, it normally involves hooking up a voltmeter between 2 of the wires on the sensor and slowing rotating the throttle from shut to full open back to shut. If the TPS is good, you will see a low voltage going to a higher one (probably 5v) and back to the original voltage with no sudden "jumps".

Sometimes, there will be a bad spot in the TPS, where the voltage will suddenly drop to 0 volts and then jump back up.

The other test is basically the same, except you monitor the TPS output using a diagnostic scanner (OBD-II hand held thing) and see what the computer is reading.

If it looks good at the tps using a voltmeter, and bad on the OBD-II scanner, then it is likely a bad connector or wiring between the ECM and the TPS. If you see a bad reading at the sensor (as I described above) then it is the sensor.

Assuming this is a 4.3. Three wires, gray=reference voltage (5v) black=ground, dark blue= signal. Hook voltmeter to dk blu and ground.
Also make sure you have ref. voltage.

 

[Nandy]

Re: 99 Blazer code p0121 and p0122

I haven't check it yet but I might have time today. When I had the throttle off I did clean it with carb cleaner while the sensor was still attached so my first guess is going to be that some of the cleaner and gunk got into the sensor and all it will take is to clean it. I also thought something might have come loose... We shall see.

 

[DECK SWABBER 58]

Re: 99 Blazer code p0121 and p0122

I haven't check it yet but I might have time today. When I had the throttle off I did clean it with carb cleaner while the sensor was still attached so my first guess is going to be that some of the cleaner and gunk got into the sensor and all it will take is to clean it. I also thought something might have come loose... We shall see.

OOOOH, you don't need to clean the TPS.

It's just a potentiometer that turns movement into a voltage
that the computer can read. You could actually have ruined
it depending on what you used as far as "carb cleaner".

Did you use "old fashioned carb cleaner" or "throttle body cleaner" ?
Their is a BIG difference.

 

[Nandy]

Re: 99 Blazer code p0121 and p0122

OOOOH, you don't need to clean the TPS.

It's just a potentiometer that turns movement into a voltage
that the computer can read. You could actually have ruined
it depending on what you used as far as "carb cleaner".

Did you use "old fashioned carb cleaner" or "throttle body cleaner" ?
Their is a BIG difference.

Well, I did clean the tps and the code went away. I did used good ol' carb cleaner. I took the tps out and notice some "dew" on it. So I use good ol' break cleaner and dose the sensor after taking it apart. One thing is that I read the sensor before cleaning it and it measure .33 when the throttle was closed and 3.84 at wot. The ground measure .02v and the source was a bit over 5v. After cleaning the max/min was the same. I did check the voltage as I was opening the throttle and it seemed fine but this is a cheap dmm so who knows...
The code is clear, that is all I needed... im leaving to va so I have no time to inspect it but will next week.
Thanks all for your help.