sasilverbullet

Almost every time I cold start the car I get these three codes, clearing them right away and they don't return the rest of the day, no matter how hard I drive the car.
Stored - P0421 Catalyst 1 Efficiency below Threshold Bank 1
Pending - P0421 Catalyst 1 Efficiency below Threshold Bank 1
Pending - P0016 Crankshaft Position - Camshaft Position Correlation Bank 1 Sensor A

The engine is a flat 6 innovation stage 2 performer that was rebuilt back in 2014. Has about 20,000 miles on it. Also has a carnual exhaust.

harveyf

Maybe this will help. I assume this started to happen unrelated to any recent changes to your hardware configuration.

harveyf

sasilverbullet

@harveyf thanks so much for all that detailed information!

I'm going to work on the crankshaft position sensor error first. I'm thinking to just order a new crankshaft position sensor and see what happens from there. That sounds smart?

harveyf

Yes.
Standard caveat, also mentioned as a potential cause for P016. Make sure your battery is up to snuff. The simple act of cranking/starting may be setting a code due to a low voltage. Keep in mind that the 987.1 Cayman is still a very analog car. Decisions are made based on percentages of a basic 12 volt signal (versus newer cars that are more digital). So if the battery voltage dips too far during cranking, certain sensors may be going below their "low" threshold values. Its really a "hack" but you might want to take another car and hook its battery up in parallel to your battery, using jumper cables. If it starts without setting codes, that would probably tell you something.

sasilverbullet

Thanks! I will definitely do that as when it cranks it seems kind of slow and I think the voltage may be dipping to 11.8 or so.

old man neri

Isn't the P0016 just 'pending'? Is it there every time after you clear it? If it's not 'stored' it could have been a 1 time glitch. Pending codes should not trigger a check engine light.

Without knowing more I would advise to deal with the P0421 first.

sasilverbullet

Battery checked good, charging correctly.
Ordered a crankshaft position sensor and two of these as recommended by Hal to fix the cat errors. https://jcarpart.com/products/90-o2-...37547405639848 He said to put them on the two upstream O2 sensors.

I'll let you all know what happens after I install them, hopefully this Saturday.

old man neri

Are you sure you're supposed to place that on the upstream sensor? I wouldn't do that if it were me. Downstream? Sure, why not. Upstream sensors are used by the car's computer to adjust(trim) the fuel amount. It's very important to have accurate readings or else you may end up running very rich or lean.

Have you looked at your fuel trim and O2 sensor readings using your scanner? Might shed light on what the actual problem is.

Schwinn

HOW did you check the battery? Checking voltages is not sufficient. Load testing can also result in false positives on these cars (I've seen it happen far too often from what I read).

How old is the battery? Has it ever been dead or low or jump-started? Do you use a battery tender? Are you in a colder climate, and has it been getting colder in your area? All of these can factor into the life of the battery and its current condition.

sasilverbullet

I have a Durametric Pro, but am very new to it. If you can explain how to check those values, I'll do that this week. ELI5 btw...

Oh, and I'm pretty sure it's running rich.

old man neri

I have never worked with Durametric so I don't think I could walk you through it.

Hal

Have you called the folks at FSI about this issue?

sasilverbullet

Had an zoom consultation yesterday with @Porschetech3 . Here's the results:
1. Both upstream O2 sensors are shut off because of a DME flash when the Softronic Intake plenum was installed.
2. I'm going to put these on the downstream O2 sensors: 90° O2 Oxygen Sensor Spacer Engine Light CEL Check Bung Mini Catalytic Converter
3. Determined that all looks good as far as cam deviation and everything else we could look at, engine seems solid
4. I'm replacing the crankshaft position sensor in hopes of fixing the occasional P0016 error.
5. Bottom line, if the O2 CEL's keep popping up, I'm going to live with it.

Shout out to @Porschetech3 , his knowledge is amazing! He's the guy that makes the UAOS. https://ultimateaos.com/

Softronic

Hello,
The P0421 code would be post O2 sensors as the pre O2 sensors are always active for fuel mixture and the post measure the Cat efficiency yet a faulty pre can skew the comparison with the post ones . Send me a email with your name etc so I can look at the file as it would be normal though and not cause a CEL for the DFI cars with a race file. Now if it was a file with emissions and the cat is aftermarket or stock and going bad could cause it. The P0016 would seam to be a part issue like the sensor etc. as mentioned.

Best,
Scott