The check engine light came on today

[pjmjr508]

I had the check eng light come on today. It had come on about a week and a half ago then went off a few hours later. Now it is staying on, so did the key dance & came back with DCT Code P 0521
which I have found to be;
P0521 Oil Pressure Switch Rationality
per a net search

So sent an email to my shop that does repairs for my warranty work.
Let you know what comes of it.

[Matt]

Edit: damnit i copied the wrong one

[Matt]

Ok let's try this again....

P0521-ENGINE OIL PRESSURE SENSOR PERFORMANCE

² When Monitored:
Engine running.
² Set Condition:
The engine oil pressure never reaches the calibrated specification with the engine RPM at 1250.

Possible Causes
ENGINE OIL/ENGINE MECHANICAL
(G6) ENGINE OIL PRESSURE SENSOR SIGNAL CIRCUIT SHORTED TO BATTERY VOLTAGE
RESISTANCE (G6) ENGINE OIL PRESSURE SENSOR SIGNAL CIRCUIT
(G6) ENGINE OIL PRESSURE SENSOR SIGNAL CIRCUIT SHORTED TO GROUND
RESISTANCE IN (F855) 5-VOLT SUPPLY CIRCUIT
(F855) 5-VOLT SUPPLY CIRCUIT SHORTED TO GROUND
RESISTANCE IN THE (K900) SENSOR RETURN CIRCUIT
ENGINE OIL PRESSURE SENSOR
PCM


Diagnostic Test
1. ACTIVE DTC
NOTE: Make sure that the engine oil is at the proper level. Also, check the customers oil change history to ensure that the oil is being changed at the correct intervals and that the proper oil viscosity is being used.
Ignition on, engine not running.
With a scan tool, read DTCs.
Is the DTC active at this time?
Yes >> Go To 2
No >> Refer to the INTERMITTENT CONDITION Diagnostic Procedure.

2. ENGINE OIL/ENGINE MECHANICAL
NOTE: The following items must be considered before determining the cause of this DTC. Failure to do so
may lead to misdiagnosis.
² ENGINE MECHANICAL TOLERANCES OUT OF SPECIFICATION
² ENGINE OIL PRESSURE OUT OF SPECIFICATION
² LOW ENGINE OIL
² OIL DIRTY OR DETERIORATED (Lack of scheduled oil changes)
² ENGINE OIL CONTAMINATED (i.e., coolant and/or fuel)
If any of the above conditions are found, repair as necessary.
Were any of the above conditions present?
Yes >> Repair as necessary.
No >> Go To 3

3. (G6) ENGINE OIL PRESSURE SENSOR SIGNAL CIRCUIT SHORTED TO BATTERY VOLTAGE
Turn the ignition off.
Disconnect the C1 PCM harness connector.
Disconnect the Engine Oil Pressure Sensor harness connector.
Ignition on, engine not running.
Measure the voltage on the (G6) Engine Oil Pressure Signal circuit in the Engine Oil Pressure Sensor harness connector.
Is the voltage above 0 volts?
Yes >> Repair the short to battery voltage in the (G6) Engine Oil Pressure Signal circuit.
No >> Go To 4

4. ENGINE OIL PRESSURE SENSOR
Turn the ignition off.
Connect the PCM harness connector.
Ignition on, engine not running.
With a scan tool, monitor the Engine Oil Pressure Sensor voltage.
Connect a jumper wire between the (K900) Sensor Ground circuit and the (G6) Engine Oil Pressure Signal circuit.
NOTE: Engine Oil Pressure voltage should change from approximately 4.5 volts to less than 0.5 of a volt.
Is the voltage reading within the listed specification when the jumper wire is installed?
Yes >> Remove the Engine Oil Pressure sensor and ensure the oil passage/port is free from any blockage. If OK, replace
the Engine Oil Pressure Sensor.
No >> Go To 5
NOTE: Remove the jumper wire before continuing.

5. EXCESSIVE RESISTANCE IN THE (G6) ENGINE OIL PRESSURE SIGNAL CIRCUIT
Turn the ignition off.
Disconnect the C1 and C2 PCM harness connectors.
CAUTION: Do not probe the PCM harness connectors. Probing the PCM harness connectors will damage the PCM terminals resulting in poor terminal to pin connection. Install Miller Special Tool #8815 to perform diagnosis.
Measure the resistance of the (G6) Engine Oil Pressure Signal circuit from the Engine Oil Pressure Sensor harness connector to the appropriate terminal of special tool #8815.
Is the resistance below 5.0 ohms?
Yes >> Go To 6
No >> Repair the excessive resistance in the (G6) Engine Oil Pressure Signal circuit.

6. (G6) ENGINE OIL PRESSURE SIGNAL CIRCUIT SHORTED TO GROUND
Measure the resistance between ground and the (G6) Engine Oil Pressure Signal circuit Engine Oil Pressure Sensor harness connector.
Is the resistance below 100 ohms?
Yes >> Repair the short to ground in the (G6) Engine Oil Pressure Signal circuit.
No >> Go To 7

7. EXCESSIVE RESISTANCE IN THE (F855) 5–VOLT SUPPLY CIRCUIT
Measure the resistance of the (F855) 5-volt Supply circuit from the Engine Oil Pressure Sensor harness connector to the appropriate terminal of special tool #8815.
Is the resistance below 5.0 ohms?
Yes >> Go To 8
No >> Repair the excessive resistance in the (F855) 5-volt Supply circuit.

8. (F855) 5-VOLT SUPPLY SHORTED TO GROUND
Measure the resistance between ground and the (F855) 5-volt Supply circuit in the Engine Oil Pressure Sensor harness connector.
Is the resistance below 100 ohms?
Yes >> Repair the short to ground in the (F855) 5-volt Supply circuit.
No >> Go To 9

9. EXCESSIVE RESISTANCE IN THE (K900) SENSOR GROUND CIRCUIT
Measure the resistance of the (K900) Sensor Ground circuit from the Engine Oil Pressure Sensor harness connector to the appropriate terminal of special tool #8815.
Is the resistance below 5.0 ohms?
Yes >> Go To 10
No >> Repair the excessive resistance in the (K900) Sensor Ground circuit.

10. PCM
NOTE: Before continuing, check the PCM harness connector terminals for corrosion, damage, or terminal push out. Repair as necessary.
Using the schematics as a guide, inspect the wire harness and connectors. Pay particular attention to all Power and Ground circuits.
Were there any problems found?
Yes >> Repair as necessary.
No >> Replace and program the Powertrain Control Module per Service Information.

[pjmjr508]

thanks Matt for the complete ts for this code.
checked oil level once I found what the code ment & level is good, plus the oil is clean. did an oil change not long ago with M1 5-20.
Also not sure if it plays a part in this but replaced the battery with a yellow top about 2 weeks ago.

[Matt]

Based on how the light came on, then went off, and is now back on.... i'd bet it's the pressure sensor. I bet ya it's cheap and easy to replace

[pjmjr508]

well I sent an email to the shop that does the work on the XK and while waiting for a reply the check engine turned off. I am thinking I should still have it looked at, but if its not on what really can they do.

What do you guys think?

[Matt]

If the lights not on they'll just have to base it off possible causes for the intermittent issue. They'll probably just look at the wiring for any evidence of corrosion or loss of insulation, and if it looks good replace the sensor to see if that resolves the problem.