2009 Dodge Grand Caravan 3.3L with engine code P1128

Question

this summer i did a replacement of spark plugs, and wires. 'then started getting the engine light coming on, diagnosed as p1128 by universal scanner. my mechanic suggested replacing the up stream and down stream o2 sensors, did that , still get engine light on after an hour driving or more, any ideas??

Answer 1

P1128 Closed loop not achieved Bank 1

This code condition occurs when the engine does not achieve closed loop from a calibrated amount of time what can affect this are coolant temperature sensor such as the thermostat. If this was a thermostat issue you would also get P1129 which is for Bank 2. If this is the only code you are getting what type of sparkplugs did you install. ? In this type of engine sparkplug makes all the difference it requires  RE14PLP5. which is a champion sparkplug. As for the thermostat ,check the coolant level make sure its at it proper level and there is no coolant leaks.

Answer 2

P1128 DODGE - Closed Loop Fueling Not Achieved Bank 1
Read more: https://www.autocodes.com/p1128_dodge.html

When the engine is cold and is started or there is a malfunction with the engine, the engine operates in “Open Loop” meaning that the Engine Control Module (ECM) will ignore most of the sensors reading and use predefined parameters set by the factory to control the engine, more specifically the engine’s air/fuel mixture. This "Open Loop" operation allows time for the engine to come up to a normal operating temperature before it starts using the information from the sensors to adjust for driving conditions. Once the engine is warm-up or reach normal operating temperature and there are no engine malfunctions, the ECM will start controlling the engine in "Close Loop", meaning that the ECM will receive the signals from the Oxygen Sensor, Coolant Temperature Sensor, and other engine sensors to control the engine's air/fuel mixture.

There are many probable causes for this code to come up, for example, lack of fuel, low fuel pressure, low engine coolant or bad coolant temperature sensor, wiring connection to other sensors, mechanical problems, and problems with the Powertrain Control Module (PCM).

Start by checking the fuel level, coolant level, fuel pressure, oxygen sensors connector, coolant temperature sensor connector, and Mass Air Flow (MAF) sensor and connector.