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Followup To
Question -
Hey John,
I have read most of your responses and I think you will be able to help me. I have a 96 Disco with 110,000 miles. The check engine light is on. I like to do my own repairs and have changed the valley pan gasket myself, so I am willing to spend time working on the disco. I love the car and hope to keep it running forever! Back to the light, after talking to the dealer service guy(who is very honest) I decided to buy my own ODB II scanner. I love it! I read and cleared the first set of codes which stated that there was a Fuel/air metering problem, a misfire on cyl 4, an ignition system failure, and a low coolent temp. After clearing, the only one to return was the fuel/air metering code, P1193. I am changing all the plugs and wires as well as the air filter and as they were due anyway. Will this help, or is it a mass air flow sensor failure or simple O2 sensor failure. Those are my intial thoughts. After thinking about it though I wonder if it could be a bad temp sensor(see low coolent temp)? What do you think?
Answer -
Hi Dean,
glad your ODBII reader is working out for you.
Your code, P1193, indicates " HO2S Heater Circuit Inferred Open Circuit, Downstream Sensors". This seems more of a heated O2 sensor problem on the exhaust side. You may want to think about where the mix problem lies and what you can do about it.
I'm not sure what is causing the O2 sensor to trigger but it can't hurt to change all those parts you mentioned, especially when they are needed.
I recently had a crack in my exhaust downpipe that triggered the O2 sensor. After welding the crack shut and resetting the system, no reading was found and it seems to be ok. BTW: The crack was at the joint just before the downpipe flange that attaches to the exhaust manifold. There was much stress there and I think its been that way since new. Strange the crack should develop so close to the original weld from the factory.
I don't think it's a bad temp sensor but its wise to check up on that low coolant temp code. Could that indicate a thermostat problem? Maybe.
The way would be to hook up your Disco to a TestBook and have it thoroughly examined. From there, it can be determined if its a MAF or sensor problem.
Best of luck,
JohnMc
NB: how much was that OBDII reader? I've seen them for about $200US.
Hey John,
My OBD was 159.00 US dollars. My LR mech said min 350 for the full test. I think I will try the O2 first. I have a welder buddy and I will check for cracks. The mech thinks maf problem. I think I will try and see if the sensors read bad first. MAF is 600 dollars. Ouch! Nothing bad can happen from trying the O2 sensors. They are not cheap though.
Thanks,
Dean
Answer******************** Follow up *****************
Hi Dean,
don't discard getting used parts for salvage yards. You can pick up a used air flow meter starting at $50US.
Try: http://www.car-part.com/
Its rare that MAF's and O2's fail, usually after extreme damage from over-heated engines. The MAF is easier to replace than the O2. You'll have to drop the downpipe (disconnect the muffler) and then probably heat up the pipe to remove the O2 sensors. Its alot easier if you have a lift!
For O2's try: http://www.oxygensensors.com/
3rd party O2's are about $80
OEM O2's are $150
If you can, look for a brake line box wrench (claw) that fits around your O2 sensor for easier removal.
Best of luck,
JohnMc
NB: good deal on that ODBII reader!
