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Solving a P2096 DTC on a flip-flop Ford

Wednesday, November 30, 2016 - 09:00
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A 2010 Ford F150 with more than 177,000 miles on its clock came in with the check engine light illuminated due to a P2096 (Post Catalyst Fuel Trim System Too Lean) DTC. This is not a DTC that is all that common to us or, for that matter, to most technicians. Usually resources such as Identifix and iATN have good information on DTCs that illuminate the MIL, but in this case there was little to nothing listed that pertained to our problem Ford. After we continued our research in ALLDATA, MotoLogic and Mitchell Pro Demand, we tried to come up with a game plan on how to diagnosis the problem.

Figure 1

It always a good idea to read up on the system description along with code setting criteria before diving in to the unknown. We proceeded to connect our scan tool and carefully review the Freeze Frame data hoping to find any clues that would lead us down the correct diagnostic path. What we found (Fig. 1) was that the Long Fuel Trim on Bank 1 was reading 20 percent while Bank 2 LTFT was at 9 percent when the engine temperature was at 185 degrees F. The Freeze Frame data also indicated that the vehicle speed was 55 miles per hour and the rpms were a bit over 1500, while Calculated Load was at 100 percent.

Is it fuel delivery?

Based on what we knew so far, it looked like a fuel delivery problem so we current ramped the fuel pump and found (Fig. 2) that the current draw of the pump was approximately10 amps. The waveform displayed an even ramping indicating an electrically healthy pump but is 10 amps a good reading or a bad reading? If the fuel pump current waveform indicated an uneven display of the commutator bar there may be a pump bushings or bearing problem that would make it a slam dunk in condemning the pump. Note that the fuel pump current reading is 10 amps since the amp clamp is set to 100mV equals 1 amp and the scope to a total of 2 volts per screen or 100 per division. Since the waveform was not conclusive in making a decision on condemning the fuel pump we had to move to the next test.

Figure 2
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