1995 gm tuck 7.4L o2 sensor contantly reads over

Limp Mode is a short term fix to get you to a garage before irreversible damage occurs. Connect it to a Code Scanner and read the codes. The codes can be searched and tell you the issue and how to fix.

Chevrolet Codes - TroubleCodes.net

https://www.troublecodes.net > chevroletcodes
OBDII Chevrolet Code Definitions. · Chevrolet Codes · P1200 - P1299 (Fuel and air metering - injector circuit) · P1300 - P1399 (Ignition system or misfire) · P1400 ...

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  GM OBD/OBD2 Codes - TroubleCodes.net

  https://www.troublecodes.net > gm
  GM Specific Codes ; 64. MAP sensor voltage low; RH side O2 sensor lean ; 65, RH side O2 sensor rich ; 66. 3-2 Control solenoid circuit fault(4L60-E); A/C pressure ...

Most Complete List For Chevy Check Engine Light Codes

https://www.engine-light-help.com > chevy-check-engi...
More than just a list of Chevy Check Engine Light Codes! ... Below you will find the most complete list of Chevy trouble codes available.

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#53 oxygen sensor heating circuit (get a new sensor)
#66 air assisted injector control circuit or circuit low
#32 oxygen heater control circuit high ( new sensor again)
theres a good chance you've several o2 sensors and I'd have to some reading on 66. I'm a chevy guy :)

MAP MANIFOLD ABSOLUT PRESSURE, MEASURE INWARD AIR FLOW OF INTAKE MANIFOLD, WORKS WITH MAF, TPS O2 SENSOR, TO GIVE THE RIGHT FUEL AIR MIXTURE, FOR MAXIMUN FUEL ECONOMY AND PROFORMANCE.

Code 44 is for the O2 sensor staying on lean, and code 45 is for the sensor staying on rich. The sensor is supposed to switch back and forth several times each minute if it is working correctly and the computer is controlling the fuel mixture.
The problem could be the sensor or a fuel problem such as an injector. The O2 sensor would need to be tested.

It will cause the fuel system to stay in open loop
& run a little rich, on a start up program


If working correctly,it will warm up & tell the ECM
so ,& the ecm then goes to closed loop, where the O2
Sensors take over the fuel injector timing or pulse width,
which can be read in a way as Short & Long Term Fuel Trim

PO 171--is an O2 Sensor Code for a Lean Condition
on Bank 1 (right side exhaust)

PO 174 -- is an O2 Sensor Codes for a Lean Condition
on Bank 2 (left side exhaust)

You gave us no vehicle
You gave us no drivability issues or
vehicle history,nothing

If the O2's have 100,000 miles on them,change the (2)
closest to the engine. They are most likely worn out
& the switching times are too slow to control injector
pulse width & thus set a MIL Lamp (OBD2 Fault ) on
your dash

You can learn a lot on the internet if you put OBD2 in your
Search Engine (Internet Explorer,etc)

how about a PO133 ,,,should be the first in system

Schematic
The Oxygen Sensor 1 (O2S-1) is an electrical source that responds to oxygen content in the exhaust manifold. When the sensor reaches approximately 316°C (600°F), it produces a voltage based on the difference in oxygen between the atmosphere and exhaust gas. The PCM sends a bias voltage (391-491 mV) on the signal line which is pulled up through high resistance. When the O2S-1 is cold, it produces no voltage and has extremely high internal resistance. The internal resistance of the sensor is much greater than the resistance of the bias pull-up resistor. However, when the sensor heats up, it produces voltage that overrides the bias voltage. This voltage is read by the PCM to determine a rich/lean O2S-1 signal used to adjust injector pulse width. Under normal conditions, low sensor voltage means high oxygen content/lean air-fuel mixture and vice versa. Normal sensor readings will fluctuate between 10 mV and 999 mV DTC P0133 sets when the O2S-1 signal rich to lean or lean to rich average response time is too slow.

DTC PARAMETERS
DTC P0133 will set if the average response time of the LEAN to RICH switches is greater than 125 ms or the average response time of the RICH to LEAN switches is greater than 156 ms for 100 seconds when:
^ Engine speed is between 1500 and 3200 RPM
^ Loop status is closed
^ Calculated air flow is greater than 7 gm/s
^ Commanded air/fuel ratio is 14.7 to 1
^ No cam, CKP, ECT, EGR, EVAP purge solenoid, fuel trim, IAT, MAP misfire, system voltage or TP sensor DTCs have been set.

DTC P0133 diagnostic runs continuously once the once the above conditions have been met.

DTC P0133 is a type B DTC.

DIAGNOSTIC AIDS
Possible causes of DTC P0133:
^ An intermittent connection or corrosion in the O2S-1 harness connector can set this DTC. Use Scan tool to monitor O2S-1 voltage with engine running at normal operating temperature while wiggling the signal and ground wire. Make sure the sensor is tight.
^ The most probable cause for DTC P0133 is contamination. Check for obvious contamination (oil, fuel or engine coolant) by removing sensor. Identify and correct the cause of the contamination if contaminated. Replace the O2S-1.
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replace the 02 upstream sensor... best solution

WOT MAF should read over 800 gs. with boost around 15psi.

If exhaust is clear and intake not plugged up with carbon...very common.... clogged injectors.

2.0 PD is self timing as long as the belt marks line up.

Also cam lobes for injectors wear out.

Still no power ? Replace injector tips/nozzles.

code 44 set on pre 1995 gm vehicles is a o2 sensor reading lean or bias to .2 volts or less. it could be the o2 sensor, it could be a vacuum leak making the exhaust have too much oxygen thus making the o2 sensor to read lean or put out a lean reading. If the o2 sensor is old 75k-100k it's probably time for a new one anyway. an exhaust leak near (upstream) to the o2 sensor can pull in air even though the exhaust is leaking out and fool the o2 sensor with the added oxygen also. you could also have a fuel delivery problem creating a true lean condition. there are ways a tech can test an o2 sensor to see if it's the sensor or a mechanical problem causing the code.