Casper2020

Hello, I had a check engine light diagnosed and it turned out to a faulty rear O2 sensor on bank 1. The mechanic said that Chevrolet issued a recommendation that all vans manufactured before Dec 2011 have issues with their O2 sensors and that I should replace all four sensors and re-flash my computer. Quote was $2000. Has anyone heard of this recommendation from Chevy? Should I have all four replaced or just replace the faulty one? Thanks.

Triaged

$2000 is a lot of money for some O2 sensors. That's what $200-300 in parts? Downstream O2 is only to make sure the Cat. is working. Check the Cat.

William Kisselstein

Tell him your wallet issued a recommendation against spending two grand for a few hundred dollars worth of parts.

MitchM

i have an upcoming appointment for my my 07 3500 express van at a chevy dealer right now. i had a check engine light, p 0300 'random cylinder misfire', ,and a code P0336 'crankshaft position sensor signal incorrect for more than 3 sec.') . an independent shop (2 miles away ) 6 months ago ran the obdIi codes and replaced both the crankshaft position sensor and the downstream o 2 sensor which was throwing a fault code. after that ckKpos S and downstream o 2 sensor replacement , the 3500 kept throwing intermittent P0336 and P0300 random misfire codes. ( the independent mechanic likely could NOT re flash the PCM and also did not even know this or tell me that might be necessary. ) . this thread has been a big help to me because if what's needed is a re-flash of PCM after an o 2 sensor replace, that might explain a lot of my recurrent p 0300 and P0336 problems.

my independent mechanic only charged me $220 to replace the downstream sensor. the other downstream sensor had been replaced a few years ago by my chevy dealer for $200. (the dealer is 22 miles away. I have to take off 1/2 day work and get a ride back and forth to the dealer to drop off and pick up...) ) The chevy dealer diagnosed a P 0300 and bad downstream o 2 sensor about 3 years ago and replaced it for about $200. (my receipt does NOT say the chevy dealer re flashed the PCM. ) the o 2 downstream sensors used to be about $100 each and an hour of labor, quite reasonable . my independent mechanic told me the 2 downstream left bank and right bank o 2 sensors are easy to get to and replace, "but the 2 upstreams are harder and can involve a lot of work to get out. " my chiltons manual p 6-20 says the o 2 sensors are easier to get out if done right after the engine's been running and the exhaust system is warm. the 2 downstream sensors and their electric connections are easy to get to and they're the ones that usually go. chiltons also suggests the electircal connections to te o 2 sensors must be cleaned and checked periodically. " and the vehicle has to be on jack stands to do this. " (i have a pair of "Rhino ramps" to elevate the back end for this job. )

chiltons says an o 2 sensor removal tool is the easiest way to get these sensors off , and the exhaust must be 'hot' for sensors to come out of the exhaust pipes easily. you also need a ratchet to fit onto the o 2 removal tool . replacing 4 sensors does not sound like a $2000 job to me . if the vehicle's already up on stands, replacing all 4 sensors at the same time shouldn't cost $2000.

does anyone know how much it costs to re-flash the PCM in an 07 3500 express ? i 'm going to ask the chevy dealer to re flash the computer. the dealer's original plan to diagnose the P 0336 and P 0300 codes was to have to put the van up on their one- and- only- truck lift, then start checking around for who knows what crankshaft position sensors and cam position sensor mis- matches.. ( my van was out of commission for 2 weeks at the chevy dealer waiting for their truck lift to get freed up so they could start diagnosing my van. ) After reading this thread the van may just need an e c u 'flash' .

so instead of waiting for the chevy dealer's truck lift to be free , then putting the van onto a truck lift and then fussing around with possible cam position sensor replacement and crankshaft re learn ( for the 3rd time ---- after TWO ac delco CkS position sensor replacements and re learns in the last 12 months .. ) my plan is now: ask chevy dealer to reflash the PCM . not just relearn the crankcase position sensor. then we ''ll see if the p 0300 and p 0336 codes go away.