P071

Code PO71:

Sensor Circuit:

Pressure Vs. Altitude Chart:

DESCRIPTION:
This diagnostic test monitors Throttle Position (TP) sensor, Engine Manifold Absolute Pressure (MAP), EGR Flow, Conditioning (A/C) Clutch status. Engine operation requires that a large change in manifold pressure must be preceded by a change in engine load due to changes in throttle angle, engine RPM, EGR flow or A/C clutch status. If TP sensor, engine RPM, EGR Flow, and A/C Clutch remain constant, and there is a rapid change in MAP, PCM Code P071 will set.

TEST CONDITIONS:
1. Code P021 and P022 not set.

2. Throttle Position (TP) sensor does NOT change more than 0.8 degree for 1.01 seconds.

3. Engine speed is greater than 500 RPM and does not change more than 100 RPM for 1.01 seconds.

4. EGR does NOT change more than 4% for 1.01 seconds.

5. Air conditioning clutch must stay 'ON' or 'OFF' during test (cannot cycle).

FAILURE CONDITIONS:
MAP Sensor reading changes more than 5.5 kPa in 12.5 milliseconds.

ACTION TAKEN:
PCM uses a substitute MAP value based on engine RPM and throttle position switch status.

NOTES ON FAULT TREE:
1. Checking if the MAP can read barometric pressure correctly (87 to 105 kPa).

2. Checking the MAP sensor ability to react to a known vacuum (26 to 34 kPa).

3. Checking the MAP sensors ability to react to a sudden change in vacuum.