1997 Ford Taurus throwing codes PO306, PO156, and PO136?

Question

3.0L V6 runs, and drives fine. "Service engine soon" light stays on. ECU throws the above listed codes. PO136 and PO156 are for the downstream heated O2 sensors. PO306 is for a misfire in the #6 cylinder. I find it unlikely that both O2 sensors should fail at the same time. The car has 239K on the clock. The common thing for all three codes is low/high fuel line pressure causing a rich or lean running situation. 

Does anyone have any ideas how to approach this problem. I feel like I might be overlooking something here. Both upstream O2 sensors appear to be alright. (this car has 4 O2 sensors, one on either side of the 2 catalytic converters). Thanks for any help.

Robert M · Accepted Answer

READ THIS CAREFULLY! Your engine has a REMOVABLE IDLE AIR CONTROL VALVE> Ford did this so you can clean it out EASILY! It is the MOST common cause of your problem. CHeaper engine oils make sludgy vapors that jamb it up inside. Once cleaned out, your O2 sensors will return to NORMAL conditions. Use POWER TUNE (from mercury boat store) AMSOIL foaming CLEANER, or SEAFOAM to clean the REMOVED IAC valve. CLean your throttle body out and run the cleaners through your PCV valve and hose. THis will clean your plug tips, piston rings, oil control rings, valve heads. O2 sensors. and remove the carbon from your expensive converter! MOTOR FLUSH your engine, and use ONLY MOBIL ONE )w-3o engine oil. Once cleaned up, your sensors should rebalance. If everything goes back to NORMAL, consider installing a set of BOSCH Fusion or Denso Iridium plugs. This will improve power, idle, MPG's and lower emissions. This will improve lifespan of converter, O2 sensors and other engine internals. Less carbon is made. GOOD LUCK! Those are some of the BEST V6 ENGINES ever made in the USA and can last another 200,000 miles! My advice should shock your sensors into full functioning again. GOOD LUCK!!

MasTec 1970 · Answer

Hello Edward, In order to give you the most accurate answer possible i need to know which 3.0L engine you have in your Taurus: the (VIN # "U") 3.0L OHV (Vulcan) V-6 or the(VIN # "S") 3.0L DOHC 24 valve (Duratec) V-6 engine?

1997 Ford Taurus throwing codes PO306, PO156, and PO136?

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