I've got both of these (1264, 1222) on one bank as well..
There is no heated o2 sensor relay in my E31 I believe.. I'm running Shogun's chips from the 750iL which do have the relay, wondering if that's the issue-- In reading some of the diagnostic procedure manuals, I recall seeing something to the effect of "if you have this error, but don't have an O2 sensor relay, it can be ignored", which leads me to believe the O2 code might not throw a CEL, but the other code may.. Looking at the E32 ETM, there is an output from the DME to a relay that might not be connected to anything in my car.. I suspect if I terminated the pin that would normally go to the O2 sensors, I could solve one of the codes. (Plus, only DME can control the O2 sensor relay)
'89 735i, '91 850i, '81 MB 380SLC (For Sale), Tesla Model 3, and VW Passat TDI -- Yes, I still repair General Modules, DM for info!
UPDATE:
Issue is still present. Code 1264 on Bank 1.
I tried replacing the 2 Main DME relays, with 2 different sets of relays. (1 set working used pulls, one set new replacements). Also tried swapping Fuse #28.
My car is a 91 850 and does NOT have the 3rd relay.
After CEL cleared, car ran for a continuous ~150 mile drive with no issues.
As before the CEL came back on within a day or two directly upon startup. (never has come on while already running).
Other than the CEL being on, the car is running beautifully and is exhibiting no mechanical symptoms.
Other note, this issue first started occurring within a few days after installing Wuffer Performance Chips Version 2.
Recap:
Replaced DME relays.
Replaced Fuse #28.
Replaced O2 sensors.
Thoughts on what to check next?
cracked wire in harness or faulty ground shielding on 02 sensor run.
'91 Dinan 860 Stage III (new 6L engine)
'91 Dinan 850 TT stage III (brand new engine) 21st Century Tech meets 18th Century Dinan...
'91 850i 6sp (mint) (sold)
'90 Dinan 750iL TT stage III (Guido - The Beast)
'94 850 CSi The Detroit Auto Show car (restored to factory perfect) (sold)
'96 850Ci, The George Carlin car
''73 3.0 csi, '08 535i, '03 X5 4.6is
...and a few other non BMW cars
Bookmarks