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Ian Tomms
Barometric sensor reading
Asked: 2 weeks, 6 days ago • Category: Frequently Asked Questions

My 2011 Jaguar fault code P0105 tells me my MAP sensor is playing up, Have replaced sensor with genuine part, have since found out that my Barometric reading is at odds with my map sensor . The car ecm reads Baro pressure at ignition stage 1 then once started the MAP sensor takes over, (I think) The ECU Baro pressure reads 199kpa?? How can I change the Baro back to the 99kpa it should read. Many Thanks

Answers

Seeing a barometric pressure reading of 199 kPa on a 2011 Jaguar at ignition-on is a red flag, this value is physically impossible under normal atmospheric conditions.

Ramphele DL
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Replies (2)

Ramphele DL : At sea level, you’re looking at roughly 100 to 102 kPa, and even at the bottom of the Dead Sea (the lowest point on Earth), it doesn’t exceed 108 kPa. So, 199 kPa suggests either a serious sensor input error or a corruption in the ECU’s interpretation of the signal. On Jags of this era, the ECU performs a barometric pressure snap shot during key on before engine start, using the MAP sensor as the measuring device since there’s no separate BARO sensor. If the intake manifold or MAP port is contaminated, restricted, or sees abnormal pressure (like a stuck open EGR or boost control issue), it can skew this reading.

Ramphele DL : But more commonly, it’s a circuit issue check the 5V reference line to the MAP sensor for voltage spikes or resistance. I’ve seen cases where a failing alternator or poor grounding introduced enough electrical noise to make the ECU think it was under 2x atmospheric pressure. Verify the actual supply voltage at the sensor with the connector plugged in (back-probing), and ensure the ground is solid less than 0.2 ohms to battery negative.

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