Oxygen sensor air fluel sensor....

[JimiRosko]

Diagnostics code read air fuel sensors and catalyst efficiency low...
It's causing the check engine light to be on.
Is it causing any damage to anything or can I keep driving it for couple weeks till I replace the oxggen sensors?
Error codes read: p0420, p1278, p1279,p1288,p1289

2008 Navara stx petrol

 

[Old.Tony]

There's a number of reasons for those codes, I'll quote from the service manual directly so I get it right - because despite having been a petrol-head for 30 years, I'm well and truly a diesel guy now!

0420 indicates a measurement problem with the air flow sensor against the heated oxygen sensor in the exhaust. This might be a faulty sensor, or even a loose or dirty connection on the sensors, but may also be a leaking air intake (so it's drawing air from somewhere between the air flow sensor and the intake manifold). Could be a dirty/faulty spark plug, or poor ignition timing, which by extension might also be a bad HT lead. It might also be a poor condition fuel injector. Liqui-Moly Injector Cleaner is awesome stuff and worth a try.

1278/1288/1289 are all bank 1/bank2 air/fuel ratio sensors. Again, possibly an intake air leak, but also might be a dirty MAFS. Remove it, spray the opening with electrical contact cleaner and avoid dropping it or inserting anything into the opening - it's extremely fragile and worth $400. Other possibilities are exhaust gas leaks, lack of fuel (possibly a crushed fuel line, or dirty filter) or the PCV hose incorrectly fitted.

Hope something in there helps. Easiest to do: MAFS cleaning. Use electrical contact cleaner or MAFS cleaner (any reasonable auto parts outlet should supply, or even Jaycar).

 

[Black_Outlaw]

Remove and clean your Mass Air Flow Sensor (its in your air-intake pipe.. right after the air filter box)

Unplug, clean / spray with Contact Cleaner the connectors that go to your O2 sensors in your exhasut.. They will be under the car.. passenger side.. almost in like with the front door. Also make sure that they are tight.. Ive never seen one become loose (usually the opposite to be precise) but there is always a first. Reset the ECU so it learns AirFlow again..

Failing that, remove the O2 sensor and check for hot spots, burn marks or any damage.. o2 Sensors do become LAZY over time and give incorrect voltage back to the ECU which then tries to richen up the AFR.. Usually a good sign of this is higher than usual fuel usage. Also check the cables themselves - you may have brushed past some debris and nicked / cut one of the cables..

Does the Navara have 1 or 2 O2 sensors? If it is 2, then try swapping the front and the back sensors. Generally in a Petrol car they run 2 sensors.. One PRE and one POST catalytic convertor. This is to ensure that (a) it's getting a good reading across 2 OS2 and 2 that the mixture passing through the CATALYTIC Converter is not TOO RICH / LEAN and burning out the CAT.. Which could also be your fault, a failed CAT Converter..