Hi all, my 2001 Discovery 2 4.0 recently popped the SES light. Runs ok, not great. Slightly extended cranking times and occasional dying immediately after starting, occasional rough shifts, just doesn't feel great in general. A month ago it had no codes and ran great, so presumably they all popped up at once. When cleared, they all pop up immediately upon starting the truck, first start. No pending status at all. System voltage sits around 14v when idling.

A scan revealed a P1884 OBD code, a deeper scan revealed the following LR codes:

• 55 - Secondary Air Valve Power Stage Fault (car is a California car and does have SAI FWIW)
• 62 - Canister Purge Valve Fault (Power Stage)
• 60 - Canister Purge Vent Valve/DMTL Power Stage Fault
• F6 - Leakage Detection Module Motor Power Stage Error
• 73 - Mass Air Flow Sensor Fault
• 70 - Camshaft Sensor Fault/Valve Timing Error

(Edit for clarity: P1884 is the ONLY OBD2 code present, it is not accompanied by anything else)

Thing is, upon viewing the live data, all of these things appear to be working. MAF reads in the range you'd expect, IAT reads within a reasonable range, the EVAP system cycles on and off properly, but unsure how to check the others. They're all labeled with "power stage fault", but I'm not sure what that means. Exhaust does not smell bad, truck does not make any funny noises, just doesn't run well.

I've checked the electrical diagrams and there doesn't really seem to be one common point between all of these.

A bit lost on where to start, hoping for some guidance.

Edit/Update:

• Grounds tested fine, very low resistance (<0.01ohm)
• I completely disconnected the MAF and it made no difference other than the live data of inlet temperature defaulted to -40*. MAF rate still reported. I'm guessing that the MAF readings I was seeing were the estimated airflow values based on TPS. Wondering if all the other codes are directly related as they expect some sort of flow rate to be able to operate properly, hence failing in the power stage.

Update 2 for future Googlers:

• Solved for now. Fuse 2 in engine bay was blown, which powers everything listed above. Replaced it and warmed up the car and it didn't blow, but will keep an eye out for it in the future.

Update 3:

• Fuse blew again as soon as I actually drove it. Found a loose O2 sensor wire that was contacting the exhaust manifold and had worn/burned through the wires - 150ohm resistance between the naked +12v wire and the positive terminal of the battery, which translates to ~10amp draw on a 15amp fuse. Explains why it would sometimes work ok, sometimes blow immediately.

 

Glad it got sorted. Thanks for posting.