2001 Nissan Pathfinder 3.5l 4X4 P1320 code accompanied by all four O2 Heater circuit codes

THEDANMAN77

MEMBER
2001 NISSAN PATHFINDER
157 MILES

Just purchased the vehicle and noticed an occasional misfire at idle, runs great otherwise. The seller previously replaced bank one sens 2 O2 sensor, plugs, and #5 coil. I also get horrible gas mileage ~14 mpg hwy and am wondering if the P1320 code is causing the P0135, P0141, P0155, and P0166 O2 heater codes. What is the most logical part(s) to change? Are my cats at risk of being fouled with this suspected rich fuel mixture? The O2 sensor was replaced almost 2 yrs ago.

3 Replies

KHLOW2008

MECHANIC
41,815 POSTS

The codes for the O2 sensors are for the heater side which means you should be testing the power supply to the O2 sensors. It could be a fuse problem.

P1320 is more likely to be related to the ignition coils and test the resistance for the coils first.

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Tuesday, October 16th, 2012 AT 7:03 AM

THEDANMAN77

MEMBER
2 POSTS

Thanks for the quick reply. I looked at all of the fuses that I thought my be related to the O2 sensors, all good. Are there any fuses other than the main ones under the hood? Is there a common connector that I can check power to those sensors? With it running in open loop, could that cause the poor gas mileage? What is nominal for highway driving on this model/year?

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Wednesday, October 17th, 2012 AT 3:21 AM

KHLOW2008

MECHANIC
41,815 POSTS

For HO2S testing.

Procedure

1. Turn ignition off. Disconnect appropriate front HO2S harness connector. See
Fig. 12 or Fig. 13. Turn ignition on. Measure voltage between ground and
appropriate front HO2S harness connector terminal No. 1 (Red/White wire). If
battery voltage exists, go to next step. If battery voltage does not exist, repair
open or short circuit and retest system.

2. Turn ignition off. Disconnect ECM harness connector. See Fig. 3. Check continuity of
Blue/Orange wire between right front HO2S harness connector terminal No. 3 and ECM harness connector terminal No. 3, or Red/Green wire between left front
HO2S harness connector terminal No. 3 and ECM harness connector terminal No.
2. See Fig. 4. Also check circuit for short to ground and short to voltage. Repair circuit as necessary and retest system. If circuit is okay, go to next step.

3. Turn ignition off. Leave appropriate HO2S harness connector disconnected.
Measure resistance between HO2S outer terminals. Resistance should be 2.3-4.3 ohms at 77°F (25°C). Check continuity between both outer HO2S terminals and
center terminal. Continuity should not exist. If HO2S does not test as specified,
replace HO2S and retest system. If HO2S is okay, go to next step.

4. No problem is indicated at this time. Problem may be intermittent.

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