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DTC codes / Chrysler codes / P1189

P1189 · ChryslerEngine Oil Pressure Switch Circuit

P1189 on Chrysler vehicles means the powertrain control module (PCM) has detected an unexpected signal from the engine oil pressure switch circuit, which is a simple on/off switch that confirms the engine has built oil pressure. The PCM monitors this circuit at key-on and during cranking, and it sets the code when the switch signal does not match the expected state for the engine speed and run time.

SystemPowertrain
Code typeChrysler specific
SeverityMedium
Fix difficultyIntermediate
AreaFuel and air metering

Symptoms you may notice

  • Oil pressure warning light illuminated on the instrument cluster
  • Check Engine Light (MIL) on with no other driveability complaints
  • Engine may enter a reduced-power or limp mode on some Chrysler models
  • Oil pressure gauge reads zero or stays pegged at maximum if the cluster uses the switch signal
  • Often no symptoms besides the warning light, especially if the switch fails open
  • Rough running or stalling only if the PCM uses the switch signal for fuel or spark scheduling

Common causes, most likely first

  1. Failed engine oil pressure switch (internal contact stuck open or closed)
  2. Damaged or corroded switch connector, especially at the oil filter housing area
  3. Chafed or broken wire between the switch and the PCM
  4. Low engine oil level or severely degraded oil causing genuinely low pressure
  5. Restricted oil filter or pickup screen reducing pressure at the switch
  6. PCM internal driver fault on the switch input circuit (rare but documented)

How to diagnose and fix it

  1. Check engine oil level and condition first; top off or change oil if it is low or sludged
  2. Inspect the oil pressure switch connector and wiring for corrosion, oil intrusion, or chafing
  3. Measure resistance across the switch with the engine off and again while cranking to confirm it opens and closes
  4. Verify oil pressure with a mechanical gauge at the switch port to rule out a real low-pressure condition
  5. Backprobe the switch signal wire at the PCM and check for voltage changes as the engine is cranked
  6. Replace the oil pressure switch if it fails the resistance or signal test
  7. Repair the harness or replace the PCM only after all wiring and switch tests pass

What the oil pressure switch test misses

  • A switch that tests good cold can fail hot, so always repeat the resistance check after the engine reaches operating temperature.
  • Oil pressure switches on Chrysler engines often leak oil through the connector body, which corrodes the terminals and sets P1189 without any external drip.
  • The PCM may set P1189 from a plausibility check against engine run time rather than a hard circuit fault, so a slow-cranking engine or low battery can trigger it.
  • Replacing the switch without verifying actual oil pressure with a mechanical gauge risks masking a worn oil pump or spun bearing.
  • Some Chrysler models share the switch ground with other sensors, so a bad ground elsewhere can set P1189 alongside unrelated codes.

Can I keep driving with P1189?

If the oil pressure warning light is on and the engine sounds normal, you can drive cautiously to a shop, but stop immediately if you hear knocking or ticking. Do not ignore the warning light, because a genuine low oil pressure condition can destroy the engine within minutes.

Tools that help

Tools we recommend are in the Auto Veteran shop on Amazon. As an Amazon Associate we earn from qualifying purchases.

Guidance is general and written for Chrysler vehicles. Exact tests and values vary by model, so confirm the fault before replacing parts.

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