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A high pressure gauge reading of 10-11 bars when backflushing is completely normal. When backflushing, the water is routed elsewhere, whether that is with a 3-way valve or another type of valve. Since the water is not escaping the grouphead like normal, there can be higher pump pressure than your normal espresso shot. Especially in machines with a vibratory pump, which can hit 15 bars or more by default, the OPV is set high enough to allow for maximum pressure when backflushing and the expected 8-9 bars when pulling an espresso shot since coffee doesn't apply as much backpressure as the blind basket.

1. If your machine has a blind basket, which is a basket with no holes on the bottom: Insert the blind basket into the portafilter, insert the portafilter into the machine, and run the pump/activate the brew lever or switch for 10 seconds to allow pump pressure to build up.
   
   If you see 8+ bars with the blind basket: The pump and machine are capable of building adequate pressure, so the issue is likely happening at the puck itself, either channeling or insufficient backpressure from your espresso preparation. Since there are no holes for water to escape through with a blind basket, any pressure loss during a real shot is coming from the coffee, not the machine. Try the following, starting with grind size if you're already filling the basket to the rim before tamping:
   

• Grind finer — a coarser grind creates larger gaps between particles, letting water flow through too easily and never building resistance.
• Use more coffee (increase your dose) — a denser, taller puck creates more resistance for water to push through.
• Increase tamp pressure — an inconsistent or light tamp can leave loose spots or cracks that water finds as a path of least resistance (channeling), rather than pushing evenly through the whole puck.
• Check for channeling directly — after a shot, examine the spent puck for visible tunnels, cracks, or wet spots concentrated in one area rather than an even, uniform saturation. This confirms water is finding shortcuts through the coffee instead of extracting evenly.
  
  If you see less than 8 bars with the blind basket, it is possible that your pump is unable to reach adequate pressure which can be because of a variety of factors. This points to the machine itself rather than your technique, since the blind basket removes puck variables entirely. Causes can include a weak or failing pump, a leak somewhere in the water path, a low or malfunctioning OPV, or mineral scale restricting flow. Check your machine's user manual to see if descaling is recommended, if it is then attempt to descale using the manufacturer's recommendations to rule out scale restricting the flow. If descaling does not help, and no leaks are visible/no water is underneath the machine, your machine may need replacement parts or repair. Seattle Coffee Gear has a repair service: Check out our repair services here. Please note: Many manufacturers do not recommend descaling at home, as getting descaling solution out of the more complex boiler/water paths can be difficult. Always be sure to check with your user manual and manufacturer recommendations before descaling.
  
  If you see no gauge movement at all with the blind basket but get adequate flow when pulling espresso shots, it is possible the pressure gauge is not functioning correctly. A replacement gauge may be necessary in this case. A machine with a non-functional pressure gauge can still be perfectly functional, many machines don't come with a pressure gauge at all. Timing your espresso shots to take ~30 seconds for 30-40ml of espresso from the time you activate the pump can be a good metric to ensure you are getting adequate backpressure and consistent results. Seattle Coffee Gear has a repair service: Check out our repair services here.
  

Machines with two gauges, common on heat exchanger (HX) and dual boiler machines, are measuring two completely different things. It's normal for them to show different numbers at the same time.

Boiler pressure gauge: This reads the steam pressure inside the boiler, often on a 0-3 bar scale. It reflects the steam and water boiler/path used for steaming milk, and on HX machines, for heating the brew water as it passes through the heat exchanger. A thermostat or PID keeps this pressure low and steady, generally around 1-1.2 bar on most home and prosumer machines.

Brew pressure gauge: This reads what the pump is generating at the group head during extraction, usually on a 0-12+ bar scale. This is the number that matters for judging shot quality, since it reflects what's happening at the puck. The needle only moves when the pump is active, pulling a shot, backflushing, or running a blind basket test, and sits near 0 at rest, unless your machine is plumbed in. If your machine is plumbed in, this gauge will read higher than 0 as it reads the line pressure of the water coming into your machine at all times.