help needed: CEL codes keep coming back but I believe parts are good

[PatrickHenry]

U.S. spec V70 base model normally aspirated 2.4 liter, 270K miles on the clock.

I need help troubleshooting check engine light issues. My car is illuminating the CEL chronically, and it’s preventing me from getting it registered. Apart from the CEL being illuminated, the car starts and drives perfectly fine.

The CEL light comes on very soon after I clear the codes (within 10 miles to 200 miles of driving).

I’m using an OBDII reader (inexpensive Actron brand code reader).

Last night I read the codes (the codes were cleared 250 miles prior to this reading) and I got the following 4 codes:
P0032
P0130
P0350
P0354
After clearing those codes, I drove it around the block last night, and drove it to the park this morning without the CEL light coming on (total of ~25miles). When I started the car to leave the park about 1 hour later, the CEL light came on. When I got home, I read the codes and I got the following 7 codes:
P0032
P0350
P0351
P0352
P0353
P0354
P0355

P0032 relates to the O2 sensor that’s installed on the top of the exhaust manifold as it exits the motor. That O2 sensor was replaced in Dec. 2018 with a Bosch 13626 oxygen sensor.

P0350-P0355 all relate to ignition coil issues but I believe the coils are operating correctly. All 5 coil packs have been replaced over the last couple of years.

Where do I begin to troubleshoot this mess of codes?

[RickHaleParker]

P0350-P0355 means the ignition coils are failing to ignite at irregular intervals. P0350 is all five coils collectively. P035X is coil X respectively. Because all five are failing to ignite, it stands to reason it is something common to all five. Check ignition coil wiring harness for defects, problems in the common power supply to the coils and grounds to the coils.

There is s good change the O2 codes are due to misfiring caused by P0350 - P0355. Fix P350-P355 first and see if P0032 & P0130 cease.

Ignition Failure is different then Misfire. However a Ignition Failure will cause a misfire. Ignition Failure means the coil did not produce a spark. Misfire means the Fuel/Air mixture failed to detonate.

Is the battery in good condition?

[abscate]

The common these to all the coils is the 12 volt supply from the main engine relay. It’s likely there is a problem between that point and the coils, perhaps in the wiring harness.

[PatrickHenry]

RickHaleParker & abscate - thank you very much for your pointers. I'll inspect the parts you've noted. Battery seems to be fine (always starts) and the battery cables in the trunk are like-new.

[PatrickHenry]

A follow-up: I cleaned up every ground connection I could find, replaced all 5 spark plugs and 1 coil pack that was visibly damaged (although apparently still firing). Those efforts helped with making some of the codes go away, but I still have one persistent code: P0032. All the other codes have not reappeared after an hour or so of driving, but P0032 keeps coming back pretty much immediately after I clear it.

I don't really understand what sets P0032. Some forum posts indicate its the sensor itself being faulty. However, I've seen other posts where the poster replaced the sensor with the factory part and P0032 reappears even with the new part, which indicates that P0032 is something other than a fault in the sensor itself.

My O2 sensor was replaced in Dec. 2018 with a Bosch 13626 sensor. What is the likelihood that replacing it again now would resolve the P0032 code?

[chrism]

Have you checked the resistance across the sensor's heater wires (with the sensor disconnected from the vehicle). I don't know what the expected resistance should be but I'll bet it's not either 1 ohm (indicating internal short) nor infinite (indicating an open circuit). Besides measuring across the two wires, also measure between each wire and the sensor body.

[RickHaleParker]

My O2 sensor was replaced in Dec. 2018 with a Bosch 13626 sensor. What is the likelihood that replacing it again now would resolve the P0032 code?

P0032 means the O2 Signal is too high.
Check the wiring to the O2 sensor for: Short-circuit to supply voltage in the signal cable.

[PatrickHenry]

chrism & RickHaleParker- thank you, I'll check.

[PatrickHenry]

Another update. I haven't had a chance to test the O2 sensor yet but have been paying very close attention to when the CEL illuminates with P0032. What I've found is that P0032 will *never* set while the car is being driven. P0032 only sets when I first start the car. If I start the car and P0032 sets and then I clear the code while the car is running, I can drive continuously for as long as I want with no codes (CEL is not lit). If I stop briefly to get gas and restart the car, no codes are set. If I park the car overnight and start it completely cold, no codes are set. But if I drive the car and then park for a couple of hours, P0032 sets when I start the car. I can then clear the code with the car running and it will not set again as long as the car is continuously driven. Weird.

[abscate]

OK, this is stimulating some ancient neuron patterns in my brain.

P0032 is the heater circuit in the front OXS, not the sensor readout. The error probably is only looked for early in the start/run cycle, so it isnt a useful diagnostic info when codes come.

Some ECM (engine computer) codes are scanned for continuously, some are only set after a 'test' is run (which can take an hour or more) and some are only tested a certain times/operating conditions.

Yeah, its complicated.

See the Major forums topics, grab the wiring diagram for your 2001, and see what else is on the OXS heater circuit. It might be another electrical fault is pulling the heater low and popping the P0032

On my ME7 equipped 1999, the Heater circuit on the OXS shares 12 Volt supply with 8/18 , 8/19/ and 8/44, which are EVAP purge valve, canister shutoff valve, and VVT solenoid valve respectively, or close-to-respectively. On all of these PIN 1, with is a GN OR wire, should show very close to B+ voltage with the key on in POS II