erratic coolant temperature with P1217 codes

[shawnnico]

Having problems with my 2003 3.5L pathfinder. Has following symptoms:
OBD Codes: P1217 Manf control Fuel Air metering - displayed twice once with the P1217 code and once with P1217p/d - whatever that means. Also has Catt eff below threshold P0420.

Starts fine but after it warms up the RPM's become erratic and the engine temperature starts to swing wildly - both at the same time, with the temperature often pegging high. On stopping the car and inspecting, I do not believe the high temperature is real - no smoking or coolant relief, doesn't smell or sound hot. Really appreciate any help.

One other symptom is that the car seems to actually run/accelerate better than normal until it warms up - very strange. Car has 210K and has been running great otherwise.

really appreciate any help /suggestions!

[zach7685]

Ill tell you what i know... a p/d code means pending. Pending means a fault was detected and wanted you to know! .... but really it it means there's an intermittent issue and will clear itself after a couple key cycles. The cat below efficiency might mean your cats are clogged. Most likely though one of your downstream 02 sensors is going bad. One tip is to try to clean the MAF sensor as-well as that can cause problems.

[Towncivilian]

Very rarely does a failed downstream O2 sensor cause a catalytic converter code, but it's a cheap $50 part vs. a more expensive cat and worth a try - even if it doesn't work, at least you have a shiny new sensor.

First, inspect your radiator cap according to this TSB. Replace with a new OEM one if necessary. Also ensure that the cooling fan operates at idle, and measure the resistance of the engine coolant temperature sensor (see EC-590. What is the coolant level in the overflow reservoir when the engine is cold? It should be at the "MAX" line. Does the coolant look brown? How has the cooling system been maintained?

Welcome to NICO.

[shawnnico]

Thanks for the suggestions - but currently the problem has gone away. I went ahead and reset the codes and connected a scanner to watch the actual coolant temperature while I drove and after 20 miles - nothing. The coolant temp lined out around 185 and no power/RPM drops. Thinking it may possibly have been a sensor short - the car had set for 12 days and we had a lot of rain - perhaps after I drove it, the connection/short dried out. Really just guessing until it happens again. Thanks

[Towncivilian]

It wouldn't hurt to inspect the rad cap and measure the ECTS resistance, it shouldn't take very long to do.

[shawnnico]

while the problem went away for 2 months it came back with a vengeance. Had to have the car towed to a dealership while travelling in Georgia. Fortunately it was a simple matter of replacing the temperature sensor - at my request. The dealership wanted to replace the radiator and thermostat. Anyway problem apparently solved - also there is only one sensor for this pathfinder and it is the input to both the dash gauge and the ECM - in contrast to some posts which indicate there are more tan one sensor. Anyway thanks for the suggestions.

[Towncivilian]

Thanks for sharing your results! Glad to hear you've got it fixed.