Rav Panesar

Hi Guys,

I have an Audi A4 on a 53 plate (B6 - 1.8T). The car has recently had its coolant temperature replaced and has now started to misfire with the CEL light on. The error displayed on VAGCOM is ...

16684 Random/Multiple misfire detected.
Cylinder #4
P0304 - Upper limit exceeded.

I have tried to clear the code but it reappears. I have since replaced the spark plugs, replaced coils, checked for vacum leaks and had the car combustion tested. The mechanic has informed me that each of the four cylinders is firing at 100 Psi.

Can anyone help please before I book this car in at Audi!????

bnr32_coupe

What kind of gas are you pumping it with? What type of spark plugs are you using? Check your spark plugs, let us know what they look like and take pictures if you can.

bnr32_coupe

edit: Take the spark plugs out and take pictures of the tips that is**

Rav Panesar

Hi bnr32_coupe,

Thank you for your prompt reply. I have managed to diagnose the fault it was in fact the coil packs two of the four coil packs were bad. I simply swapped the coils and identified the issue. I have since cleared the fault and everything appears to be okay for now other than the following new error!

16804 - Catalyst system: Bank 1: Efficiency below threshold.
P0420 - 002 - Lower limit exceeded.

I am somewhat hesitant to go straight in and replace the lambda sensor located on bank 1 as I have a sneaky suspicion that this may be related to some cat cleaner that I have used since replacing the coils. Before the coils on my car were replaced I noticed that the catalytic onvertor on my vehicle was glowing bright red! - due to two bad coils.

Lets see how things go! Once again thanks for your help.