P38A Fault Codes.. the saga continues

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ukadamwest

ukadamwest

Well-Known Member
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Location
Surrey
after Martin did the heater core, Martin and I noticed the P38 was slightly down on power.

Last week or so, the wife returned home with a rattling cat. tapped it with a rubber mallet and yes it was gone. After removing it I cut it up and the internal matrix was pretty much collapsed.. that'll be a reason for being down on power!

after much buggering about with the wrong cat being delivered, collected etc. i've got the new cats on and new o2 sensors.

however its running like a pig.

fault codes are

P0135 - O2 heater sensor circuit bank 1
P0155 - O2 heater sensor circuit bank 2
P0134 - O2 Sensor Circuit No Activity Detected
P1300 - Multiple Cyl misfire
P0304 - Misfire Cyl 4
P0303 - Misfire Cyl 3
P1000 - Misfire Cyl 6

Its a 4.6 thor, on petrol
 
Last edited:
ukadamwest said:
after Martin did the heater core, Martin and I noticed the P38 was slightly down on power.

Last week or so, the wife returned home with a rattling cat. tapped it with a rubber mallet and yes it was gone. After removing it I cut it up and the internal matrix was pretty much collapsed.. that'll be a reason for being down on power!

after much buggering about with the wrong cat being delivered, collected etc. i've got the new cats on and new o2 sensors.

however its running like a pig.

fault codes are

P0135 - O2 heater sensor circuit bank 1
P0155 - O2 heater sensor circuit bank 2
P0134 - O2 Sensor Circuit No Activity Detected
P1300 - Multiple Cyl misfire
P0304 - Misfire Cyl 4
P0303 - Misfire Cyl 3
P1000 - Misfire Cyl 6

Its a 4.6 thor, on petrol
Click to expand...
 
was it just cat failure at first? I take it you changed the o2's as a matter of course. I.e seized in the pipes? If there were no codes before you changed the pipes and sensors, your sensors could be the issue! Or even the wire configuration in the plug??
 
Don't rely on fault codes. Check if the o2 sensor outputs are changing up/down. Rate should vary with engine revs. It's one of the few things generic diagnostics will read.

If they are not then recheck wiring. Were they plug & play, or wire end type?

Pete.
 
Hi dave..

yep problem resolved.

when martin did the heater matrix, we noticed it was slightly down on power... well it turns out the cat was dying a death so the pressure from a broken down cat matrix was causing the power loss. hence replacing the Cats and the O2 sensors.

I replaced the HT leads and plugs today, which is a ballache in itself as the LPG heater pipes run across the bulkhead, so its a case of dropping the coolant out.. again and then a few weeks of burping.. or lift the inlet manifold.

lifted the inlet manifold !

two of the HT leads, 3 and 4 were breaking up at the coil end.. hence the fault codes. The P38 is now back and goes like frigging stink.. With no heater matrix woes.. so this year she has had....

top end rebuild with new head gaskets
new battery
new alternator module
new cats
new uniroyal rainsport 3 all round
new brake discs and pads all round
new viscous fan
new pulley
new waterpump
new ht leads
dash out and the heater matrix replaced and all flaps checked and sorted (courtesy of Martin)

aaaaand now the wife has decided its a bit big for her so likes the idea of an Audi A3
 
Were the O2 sensors genuine Bosch ones, or aftermarket?

Aftermarket ones seem to always throw up heater circuit codes...

Glad the plugs and leads have sorted things out though!
 
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