Check Engine Light On - On Star Diagnostics

[giveusroom]

I've had my Volt for a month and it's been fantastic. However, my check engine light came on last night. I did not notice any other symptoms and the Volt drove home just fine. The closest authorized Volt dealer (at least with any experience) is 90 miles away. Can I get a code read by using On-Star? Is it OK to ignore this for a few days to see if it goes away? Any advice?

[Stilgar99]

Dont ignore it. Use Onstar asap to have the tell you the exact 'diagnostic code'. (get the exact number so that folks here can help you). The Onstar advisor may tell you to go straight to your dealer. I would check here first (some code are not that bad...and some even seem to reset), however I would advise you do not drive the car much until you get more data.
Once you get the code, post it here and folks may help if they have even seen it before....

Stilgar

[giveusroom]

I talked to On Star. The code is P0D22 - Battery Voltage Sensing Error. They advised me that I might not be able to charge the Volt. Not true. The Volt charged just fine. I don't notice anything wrong. I think it was a voltage measurement glitch. One thing I did do a couple of times is unplug the Volt after it was fully charged and then plugged it back in immediately. Makes me wonder if this caused the glitch. Anybody know anything about this code?

[Slapshot28]

I had the exact same thing happen, from the exact same cause (unplugging/replugging with full charge, 120V connection).

Unless GM says otherwise, you are okay and the CEL should turn itself off after 2-3 days. It is a bit disconcerting, but at least we know the car is being sensitive!

Since then I've just left the Volt plugged in at all times, unless I'm ready to go!

Chris

[WopOnTour]

I talked to On Star. The code is P0D22 - Battery Voltage Sensing Error. They advised me that I might not be able to charge the Volt. Not true. The Volt charged just fine. I don't notice anything wrong. I think it was a voltage measurement glitch. One thing I did do a couple of times is unplug the Volt after it was fully charged and then plugged it back in immediately. Makes me wonder if this caused the glitch. Anybody know anything about this code?

DTC P0D22 is actually titled: Battery Charger Output Current Performance. Typically it would be detected and set during charging it should first A) temporarily disable charging (until the next charge cycle) and B) brings on the Check Engine Lamp (MIL) on the next drive cycle.

Basically P0D22 indicates that during the charge, the measured charging current was not within certain parameters over a defined period of time. If your Volt appears to be charging normally then the fault is no longer present.

I am wondering about the repeated disconnects-reconnects though. I suppose it might have created a false fail somehow. If it sets again you'll definately want to take it to your dealer.

WopOnTour

[giveusroom]

I did a search and found the other thread about CEL codes and specifically this code that Chris had. It makes me suspect an unanticipated scenario by the developers with this error - plugging in when Volt is fully charged. That might cause the charge current to never reach the expected levels within the 40 seconds and an error is flagged, but the reality is that the Volt is simply fully charged. There needs to be a check on the voltage before flagging the error. If the voltage is above a certain threshold, the error should not be flagged. Or perhaps that is already done, but the threshhold needs adjustment. Or maybe I'm way off.

[WopOnTour]

I did a search and found the other thread about CEL codes and specifically this code that Chris had. It makes me suspect an unanticipated scenario by the developers with this error - plugging in when Volt is fully charged. That might cause the charge current to never reach the expected levels within the 40 seconds and an error is flagged, but the reality is that the Volt is simply fully charged. There needs to be a check on the voltage before flagging the error. If the voltage is above a certain threshold, the error should not be flagged. Or perhaps that is already done, but the threshhold needs adjustment. Or maybe I'm way off.

I agree. There might also be an issue with the enable/fail criteria as documented in gSI.
But my understanding was when the charging was in voltage regulation mode (initially and during the finish of charging) the P0D21 would set if charging voltage wasnt correct, but when in current regulation mode (during the majority of the charge cycle) then P0D22 sets if measured charging current was not correct. (a you said for 40 seconds)

I've unplugged and plugged in the car while charging AND when fully charged (both repeatedly) and never had this DTC set falsly, but it might still under very specific conditions that we've yet to define. If it is false it's nothing that software can't rectify of course, so that's why I'd suggest a dealer visit (if not TOO inconvenient) even if it doesnt reset as it needs a case# to get something happening.Plus there should be a Freeze Frame that would indicate the conditions present when the fault was detected.

But there's also a recent (since SOP) update for the onboard charger control module listed in TIS2WEB. It's titled "OBD II diagnostic software and calibration changes". I'll try and find out exactly what it specifically addresses but if you took it to the dealer they could easily determine if you have this update already.
HTH
WOT

[giveusroom]

Thanks to all of you for responding on this thread. This forum is golden for Volt owners. Thanks WOT.

[Chevrolet Customer Svc]

Wanted to let everyone know that it is not necessary to bring a Volt to a dealer with a P0D22 code at this time, as long as there are no charging complaints.

Thanks,
Caron - Chevrolet Volt Advisor
socialmedia@gm.com

[giveusroom]

My CEL went out today. Car is fine. No problems with charging at any time, including when the light came on. Again, thanks for the information and advice. I love my range extended electric car.