Dang Check Engine Light!
 

2003 Land Rover SE, 84,000mi.

New Bosch Mass Airflow Sensor, New pre-cat Bosch O2 sensors, K&N air filter, 5W30 synth, engine rebuilt approx. 40K. Looks like new spark plug wires (blue).

OBD-II codes: P1170, P1174

Here's sequence of events:

MAS sensor replaced in May 2013- no check engine light
I bought the car in July 2013 - no check engine light
I replace with K&N air filter July 2013
I replace engine oil Aug 2013
Check engine light comes on Aug 2013 gives me P1170 and P1174
I replace both pre-cat O2 sensors with correct Bosch O2 sensors
Check engine light comes on Aug 2013 gives me P1170 and P1174



I have reset the codes but they keep coming back on. What is the issue?

K&N may have killed the MAF Sensor... or you may not have the air box lid closed all the way.

If using a KN, should I replace the MAF sensor?

If the K&N filter was over oiled it can kill the MAF, you can try cleaning it with MAF cleaner and see if that helps... but I am not a fan of K&N filters, I have seen them do more harm then good unless oiled correctly.