Swapped in a new (old) 305 last weekend after blowin up the old one. I can't get by emissions and to top that it threw a code while I was sitting in line to get sniffed. Long story short- code 13(O sensor) and a code 44(O sensor lean). Does the 13 mean that the O sensor is bad or just that it detected something (the code 44)? Any and all help greatly appreciated.

P.S. How do all you guys with gutted cats (or no cats) ever get past emissions? Does every state have emissions tests?

 

WD,

The '13' means that the ECM is not getting even a minimal level signal from the oxygen sensor. This could mean a failed sensor or a poor electrical connection (including the all-important grounding of the exhaust pipe). Check the connections first, and make certain the exhaust system is grounded. If you have a DMM you can test the sensor fairly easily. Remove the sensor and connect the voltmeter on a 2.0VDC scale. Hold the sensing element end in the flame of a propane torch while measuring voltage. The sensor should produce a signal of at least 0.75VDC. Removing the flame should drop the sensor output to nearly 0VDC. This does not test the quality of the sensor, but will tell you if it is completely "dead" or not.

Once you repair the system the code '44' should disappear.

As for passing inspections with no cat, a properly running engine can pass in some areas (depending upon the acceptable emissions levels) but may not pass in all areas. If your inspection/test incluides a visual inspection, you'll probably never get through the lane with a sticker.

Not all states have required inspections. Larger metropolitan areas have federally mandated inspections and some states have decided to standardize their requirements to include the entire state. In illinois, for example, only the Chicago and St. Louis metro areas have required inspections.

------------------
Later,
Vader
------------------
"Let the bodies hit the floor!"
Adobe Acrobat Reader

 

I often see these codes alot. The code 13 usually means a "lack of switching". A normally operating O2 sensor switches very rapidly. If the ECM does not see this rapid switching, it will know something is wrong.

Code 44 is "lean exhaust". I see this w/ code 13 alot because the O2 sensor generates its own voltage based on oxygen content of the exhaust. The ECM normally applies a bias voltage of 450mV to the sensor. If the exhaust is lean, the sensor does not generate voltage and acutally pulls the bias voltage "low". When the ECM sees the bias voltage drop below 450mV, it knows the exhaust is lean. When the exhaust is rich, it generates voltage, and raises the bias voltage to above 450mV. When the ECM sees this rise in voltage, it knows the exhaust is rich. However, when a sensor dies, it is incapable in generating voltage and pulls the bias voltage low (code 44) and keeps it there, causing a lack of switching (code 13). See how that works? OK pop quiz time...

------------------
FREE CARFAX Record Check

If you live in Southeastern US, check us out!
South East Thirdgen

GM Master Tech
ASE Master Tech + L1
Savannah, GA

'87 Trans Am
S/D TPI retrofit including functional PassKey,
22# injectors,
Whatever chip I feel like burning,
JET AFPR, Ported Plenum,
TB Coolant Bypass, Custom Cold Air,
SSM SFC, KYB Shocks, Boxed LCAs, Wonder Bar,
8mm Accel wires,
Flowmaster Exhaust,
16" GTA rims,
Corvette Servo,
3.73 Posi
4wheel Disc Brakes
Summit 1-5/8" headers, 2.5" Dynomax catback.

Best 1/8: 9.519@72.74

'97 Bonneville SSE

 

Right on, guys, those are the two clearest answers I've ever been given here. (And it's what I wanted to hear!) I decided to just replace the sensor anyway, but you got me with the grounding of the exhaust. What's up with that? Thanks a mil....

 

In order for electricity to flow, there must be a complete circuit. There needs to be a "positive" and "negative". If you notice, your O2 sensor only has one wire, and in this case, would be considered the "positive". (remember, when its rich, its feeding voltage to the ECM)

In order for it to send out voltage, it must also have a "negative". Since there are no other wires coming from the sensor, it uses the casing of the sensor itself as a ground. It is threaded into the exhaust, and the exhaust is bolted to the engine, thus providing an "engine ground". Sometimes you can get a rusted exhaust doughnut and get a poor ground, but this doesn't happen often. If ever in doubt, you can wrap a bare wire around the outside of the sensor, then run the other end to the neg batt terminal, for testing purposes. I think your new sensor will fix it though.

For $hits and giggles, if you have access to a scantool or Volt Meter (capable of reading mV) to see just how senstive the O2 signal is, monitor the O2 signal, w/ your bare hand, grab the purple signal wire, then take your other hand and touch the NEG batt terminal, and watch the mV sink like a rock. Then touch the POS batt terminal w/ your finger, and watch it peg @ 1000mV. Thats why they tell you not to route plug wires near that wire.

------------------
FREE CARFAX Record Check

If you live in Southeastern US, check us out!
South East Thirdgen

GM Master Tech
ASE Master Tech + L1
Savannah, GA

'87 Trans Am
S/D TPI retrofit including functional PassKey,
22# injectors,
Whatever chip I feel like burning,
JET AFPR, Ported Plenum,
TB Coolant Bypass, Custom Cold Air,
SSM SFC, KYB Shocks, Boxed LCAs, Wonder Bar,
8mm Accel wires,
Flowmaster Exhaust,
16" GTA rims,
Corvette Servo,
3.73 Posi
4wheel Disc Brakes
Summit 1-5/8" headers, 2.5" Dynomax catback.

Best 1/8: 9.519@72.74

'97 Bonneville SSE