I took my beater van out for a drive for 60 miles yesterday. I topped up when I left and again when I returned and I burned through $42 in (regular) gas. That works out to 6.7 mpg, and that was 90% highway driving (when new it was rated at 24mpg highway).

What could be causing such horrible gas mileage?

I hooked up Torque and it was flashing:

p0125 - "insufficient coolant temperature for closed loop fuel control"

and

p0135 "o2 sensor heater circuit (Bank 1, Sensor 1)"

I cleared the codes and they haven't returned but I haven't driven it again, just idled it for a few minutes. I did have an overheat last week, the coolant was low so I topped it up and she's running fine as far as temp is concerned (did not continue to drive when overhot; I also "burped" the air bubbles out of the system by using the plastic bottle trick - very effective!).

I hooked up Torque again this afternoon and no codes were flashing. But then I used an old school, hand-held variety I found lying around, and it did show codes: P0135 - O2 sensor (like before) and P0463 - Fuel Level Sensor A Circuit High Input

The Fuel Level issue doesn't surprise me as these vehicles are notorious for failing fuel gauges. This van is worth less than $1000, I only use it for garbage/building materials runs -- but at 6mpg it's no longer a "cheap" beater. Any thoughts on what to tackle first? I'm new to Torque and frankly overwhelmed by the amount of data I can access, not sure where to start. I'm not set up for major repairs, but I'm thinking of swapping out the air filter, thermostat, thermostat temp sensor. But with the O2 sensor - do I replace upstream or downstream or both?

Thanks for any advice.

 

if the coolant doesn't get hot the van will run rich mixtures. monitor the coolant temp with your scan tool...it should be getting to 90* C. at that point the thermostat should be open and the upper rad hose should be hot...if it doesn't...change the thermostat. usually vehicles set p0128 when the coolant doesn't reach a set temp in a set run time.

check the 02 heater fuse...if its good...inspect the 02 wiring...if its good replace the 02 sensor. replace just the one sensor b1s1 upstream on cylinder #1 bank