P0191 Fuel rail pressure sensor reading does not make sense

Fuel Rail Pressure Sensor A Circuit Range/Performance

P0191 in short

P0191 means the fuel rail pressure sensor's reading does not match what the engine computer expects. The sensor or its wiring is a common cause, but bulletins also blame a weak high-pressure pump, contaminated fuel and computer software. Get it diagnosed soon, and stop driving if the engine stalls or loses power.

The rail pressure sensor tells the engine computer how much pressure is in the fuel rail. The computer feeds it 5 volts and reads a signal that rises with pressure. P0191 sets when that reading is in electrical range but does not fit what should be happening, such as pressure that stays too high or too low compared with what was requested.

So the code can mean the sensor is wrong, or that the pressure really is wrong. Saab lists wiring breaks, corrosion and loose pins; Mazda found high-pressure pumps that could not reach target pressure; GM found fuel contamination and, on some trucks, pressure that drops too slowly after shut-off.

P0191 is used on both petrol and diesel engines. Bulletins cover Volkswagen and Audi TDI diesels, Ford and GM trucks and vans, and Ram 5.9L diesels, as well as direct-injection petrol engines.

Most likely causes

  1. Rail pressure sensor or its wiring and connector

    Common general cause
    Why it ranks here
    The code is a plausibility check on this sensor. Saab's service information lists wiring breaks, shorts, corrosion and loose pins, and a GM bulletin traces intermittent P0191 on 2006–2009 trucks and vans to harness connections.
    What would change this
    Rises if the reading jumps when the harness is moved or the 5 V reference or ground checks fail. Falls if the circuit tests good and the reading matches a gauge.
    How to test the fuel rail pressure sensor

  2. High-pressure fuel pump not reaching target pressure

    Supported by vehicle data
    Why it ranks here
    Mazda traced P0191 on 2012–2014 Mazda3, CX-5 and Mazda6 to a pump with a manufacturing fault, and GM has technicians check for a non-original pump when 2010–2017 models stall with P0191.
    What would change this
    Rises if actual pressure stays below desired under load, or the pump is not an original part. Falls if pressure tracks desired.
    How to test the fuel pump

  3. Contaminated fuel or debris in the fuel system

    Supported by vehicle data
    Why it ranks here
    GM bulletins for trucks, vans and some cars tie hard starting or no start with P0087, P0088 and P0191 to debris in the fuel system, and call for cleaning the whole system.
    What would change this
    Rises if a fuel sample is dirty or the filter is clogged. Falls if the fuel tests clean.

  4. Engine computer software (some models)

    Supported by vehicle data
    Why it ranks here
    Genesis updates the engine computer for P0191 on the 2022–2023 G70 2.0T, and Dodge did the same on the Ram 5.9L diesel.
    What would change this
    Rises if the dealer finds a newer calibration for the VIN. Falls if it is current.

  5. Rail pressure not dropping fast enough after shut-off (some GM trucks)

    Supported by vehicle data
    Why it ranks here
    GM says P0191 can set on its trucks and vans when rail pressure does not fall quickly enough after the engine is turned off.
    What would change this
    Rises if the code sets at key-on after a recent shut-off. Falls if pressure decays normally.

  6. In-tank fuel pump or fuel pump control module

    Possible — needs testing
    Why it ranks here
    GM-based service information for the Saab 9-4X says a fault in the in-tank pump module or the pump control module can set P0191. No bulletin we found names it, so it needs testing.
    What would change this
    Rises if low-side pressure is low or the pump control module has codes. Falls if supply pressure is in specification.
    How to test the fuel pump

What to test first

Start at step 1. Each result tells you what it means and where to go next.

  1. Read all codes and freeze-frame data, and note any P0087, P0088, P0089, P0172 or P128E stored with P0191.

    Low riskTool: OBD-II scan tool

  2. Ask a dealer to check the VIN for engine computer updates and fuel system bulletins.

    Low riskTool: VIN lookup at a dealer

  3. With a scan tool, read rail pressure with the key on and engine off, then compare actual with desired pressure at idle and as a helper raises engine speed. Move the sensor harness gently while watching the reading.

    Use cautionTool: scan tool with live data

    Warning:Run the engine outdoors and keep clear of belts and the fan. Never loosen a fuel fitting: the high-pressure side can hold pressure after shutdown and a fuel spray can cause injury or fire.

  4. Have a shop check low-side supply pressure, take a fuel sample and inspect the filter.

    Best left to a shopTool: fuel pressure gauge

    Warning:Run the engine outdoors and keep clear of belts and the fan. Never loosen a fuel fitting: the high-pressure side can hold pressure after shutdown and a fuel spray can cause injury or fire.

Symptoms

  • Check engine light on
  • Hard starting or long cranking Gets more serious: stop and have it checked.
  • Hesitation, rough running or lack of power Gets more serious: stop and have it checked.
  • Engine stalls Gets more serious: stop and have it checked.

Compare with: Check engine light with loss of power

How to fix

  1. Ask a dealer to check the VIN for software updates and fuel system bulletins before buying parts.

  2. With the engine off, look at the rail pressure sensor connector for a loose fit or corrosion, without disconnecting any fuel line.

Parts and cost context

  • Fuel pump:A pump is only the answer when pressure tests show it cannot reach target; the sensor, wiring and fuel quality are checked first. Labour varies; get a quote.

Labor varies by vehicle and shop; get a quote before you approve a repair.

Compare used part prices on PartPriceGuide

On your vehicle

Mazda

  • 2012–2014 · CX-5

    Supported by vehicle data

    Also Mazda3 and Mazda6: a high-pressure pump manufacturing fault kept pressure below target. Bulletin status not verified.

  • 01-010-14-2896Status unverified

    MIL with DTC P0191:00

    2012–2014mazda3, cx-5, mazda6 · issued · NHTSA 10098207

    High-pressure fuel pump not reaching target pressure due to a manufacturing fault.

    We couldn't confirm whether this bulletin is still current, so it doesn't count as confirmation.

Chevrolet

  • 2010–2019 · Equinox

    Supported by vehicle data

    Stalling with P0191 (and sometimes P0172) on 2010–2017: check for a non-original high-pressure pump. Later models appear in GM's fuel contamination bulletin. Bulletin status not verified.

  • 2006–2017 · Express

    Supported by vehicle data

    Intermittent P0191 from harness connections on 2006–2009; hard or no start from fuel contamination on later vans. Bulletin status not verified.

  • PIP6113Status unverified

    Stall with P0191, may also set P0172

    2010–2017equinox, malibu, terrain · issued · NHTSA 11032947

    Check that the high-pressure pump is an original part.

    We couldn't confirm whether this bulletin is still current, so it doesn't count as confirmation.

  • 16-NA-102Status unverified

    Hard start or no start with P0087, P0088, P0191 or P128E

    2012–2016express, savana, silverado-2500 · issued · NHTSA 10081221

    Debris in the fuel system; inspect and replace fuel parts.

    We couldn't confirm whether this bulletin is still current, so it doesn't count as confirmation.

  • PIP5151FStatus unverified

    Hard start, no start, rough running or low fuel pressure

    2010–2019express, silverado-1500, cruze, equinox · issued · NHTSA 10143785

    If contamination is found, clean and flush the whole fuel system.

    We couldn't confirm whether this bulletin is still current, so it doesn't count as confirmation.

  • TB-09-06-04-022Status unverified

    Intermittent P0191, slow rail pressure decay

    2006–2009express, silverado, savana, sierra · issued · NHTSA 10030110

    Wiring harness connections and voltage interruptions.

    We couldn't confirm whether this bulletin is still current, so it doesn't count as confirmation.

Ford

  • 2006–2007 · E-Series

    Supported by vehicle data

    5.4L/6.8L with aft-axle tank built before 07/16/07: P0191 with crank/no start or lack of power. Bulletin status not verified.

  • 19882Status unverified

    P0191 with crank/no start, hesitation or lack of power

    2006–2007e-series · issued · NHTSA 10023298

    E-Series 5.4L/6.8L with aft-axle tank built before 07/16/07.

    We couldn't confirm whether this bulletin is still current, so it doesn't count as confirmation.

  • 05262Status unverified

    MIL on with DTC P0191

    2004–2005explorer · issued · NHTSA 10018937

    Explorer and Mountaineer with P0191, with or without drivability symptoms.

    We couldn't confirm whether this bulletin is still current, so it doesn't count as confirmation.

Volkswagen

  • 2009–2014 · Jetta

    Supported by vehicle data

    TDI diesels only: no start or rough running with P0087, P0088 or P0191. Bulletin status not verified.

  • 231402Status unverified

    MIL on, no start or rough running with P0087, P0088 or P0191 (TDI only)

    2009–2014jetta, passat, golf, touareg · issued · NHTSA 10239817

    TDI diesels only.

    We couldn't confirm whether this bulletin is still current, so it doesn't count as confirmation.

  • P0087Fuel pressure in the rail or supply system is lower than the engine computer requested

    Shares causes Supported by vehicle data

    GM, Volkswagen and Audi bulletins list P0087 with P0191 when contamination or the fuel supply leaves the engine short of pressure.

  • P0172Engine computer has reached its limit removing fuel on bank 1: the mixture is rich

    Shares causes Supported by vehicle data

    On some 2010–2017 GM models that stall with P0191, P0172 may set too; GM checks for a non-original high-pressure pump.

  • P0089Fuel pressure regulator not holding the pressure the computer asks for

    Same system Common general cause

    P0089 flags pressure not following the regulator's target; P0191 flags the sensor reading as implausible. They check the same pressure from two sides.

All Turbocharging, fuel pressure and EGR codes

P0191 questions

Is it safe to drive with P0191?

Only to get it checked, if it runs normally. Bulletins link the code to hard starting, lack of power and stalling, so stop if any of those happen.

Is P0191 always the sensor?

No. The code means the reading does not make sense, which can be a bad sensor or wiring, or real pressure problems from the pump, contaminated fuel or software.

Sources and review

  1. P0191 00: fuel rail pressure sensor circuit performance problem, 2012 Saab 9-3 service information — Saab Automobile (Saab WIS Online)
  2. P0191 with crank/no start, hesitation or lack of power (bulletin 19882) — Ford Motor Company / NHTSA ,
  3. Hard start or no start with P0087, P0088, P0191 or P128E (bulletin 16-NA-102) — General Motors / NHTSA ,
  4. Stall with P0191, may also set P0172 (bulletin PIP6113) — General Motors / NHTSA ,
  5. DTC P0191 (LF1, LFW), 2011 Saab 9-4X service information — Saab Automobile (GM-based service information, Saab WIS Online)
  6. Intermittent DTC P0191, slow fuel rail pressure decay (bulletin TB-09-06-04-022) — General Motors / NHTSA ,
  7. MIL with DTC P0191:00 (bulletin 01-010-14-2896) — Mazda North American Operations / NHTSA ,
  8. Hard start, no start, rough running or low fuel pressure (bulletin PIP5151F) — General Motors / NHTSA ,
  9. Check engine light with DTC P019100 (bulletin 26-01-007G) — Genesis Motor America / NHTSA ,
  10. 5.9L DTC P0191, fuel pressure sensor rationality (bulletin 1803206) — FCA US LLC / NHTSA ,
  11. Fuel rail pressure sensor performance DTC P0191 (bulletin PIP-4430) — General Motors / NHTSA ,
  12. MIL on, no start or rough running with P0087, P0088 or P0191 (TDI only) (bulletin 231402) — Volkswagen of America / NHTSA ,
  13. MIL on, rough running or no start with P0087, P0088 or P0191 (bulletin A232357204075211) — Audi of America / NHTSA ,
  14. DTC P0089, P00C6, P228C, or P228D (LF1, LFW), 2011 Saab 9-4X service information — Saab Automobile (GM-based service information, Saab WIS Online)
  15. On-Board Diagnostic Trouble Codes (generic code title list) — Delaware Division of Motor Vehicles
  16. MIL on with DTC P0191 (bulletin 05262) — Ford Motor Company / NHTSA ,
Last reviewed
Written by
Saurabh K.
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