Car starts harder than it should and is rough first couple minutes and GP light comes back on. Read the trouble codes and they pointed to the 5+6 GP's Followed Dieselgiants instructions on checking the GP's on my car. Here is the situation, his instructions say to connect the negative lead from the meter to the negative post on the batt. In the 210, the batt. is under the back seat. Can I just use part of the frame or motor as a ground? Doing it this way I got the following readings on my analog meter: GP's 1-4, O ohm (I was looking for ~.5 or so). When connected to 5+6 I got infinity. I gather 5+6 are my bad plugs. But why would the first 4 read 0? Because I didn't have sufficient ground? Or would this be normal for an analog meter. BTW the meter has ohm adjust and was zeroed prior to the test. Am I correct in concluding that 5+6 are bad the the other 4 are OK?

TIA, any help is appreciated.

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Muleears
'07 E320 Bluetec 133K my DD
'04 Jaguar XJ8 VDP, 34K
'10 Hyundai Accent 60K Grocery Getter
'02 VW Golf soon to be on the road again
'97 E300 Diesel Son's DD
'61 VERY tolerant wife

Hampton Roads, VA USA

Gone but not forgotten:
'67 250S 95K
'86 300SDL
'87 300D Turbo, 364K! R.I.P.
'98 E300 Turbodiesel, 213K
'02 S420, 164K
'01 Prius 138K