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Curious MAP sensor failing - symptoms


NAXJA Forum User
London; UK
Rather than a call for help this post is more to assist anyone experiencing the following symptoms and searching for a possible reason.

This is my own experience with an Mopar MAP sensor (p/n 56028303) fitted to a 1996 4.0 in June 2017 i.e. 5+ years ago:

Prior to this vehicle has been running faultlessly and all grounds already sorted with Jeep Cables Big 7 (highly recommended):

-June '23: vehicle had travelled 30 + miles at highway speed and during 5-10 mph suburban crawl engine cut out and all power lost; all guages died.
After 10 mins checking battery; cabling etc. restarted first time.
Error code 14 showed up after 3 cycling ignition key but disappeared after next re-start :confused:

-July thru' early September: no issues - approx. 900 miles travelled.

- Sept: after approx 5 miles in urban then suburban traffic engine stumbled for second or so but engine continued to run. CEL showed for first time and threw code 14. After 10 mins and clearing with battery disconect CEL remained off.
Bluetooth battery monitor had stored a significant voltage drop to c. 11.0 volts:

- Yesterday: Following 50 mile drive I was doing (unrelated) work under hood and after 5 mins of idle engine died, CEL came on and gave up a single code 14. Starter motor would spin up but engine would die immediately.

Followed diagnosis (see link below) confirmed 5v was reaching MAP sensor and earths were good.
Relaced sensor with original (OE) MAP sensor removed when fitting failed (OE) unit back in 2017. Replaced OE rubber hose with inch of 3mm silicone hose.


No return of code 14 during 90 mile trip (highway & urban) and vehicle runs strongly and smoothly.

Conclusion: Even OE sensors can fail prematurely. That said, this sensor was 9 years old (according to build date on box) so really 15+ years old when it failed!
MAP sensor failure was progressive and intermittent.
In retrospect, now the replacement sensor has been fitted, the engine had been very slightly down on power and didn't run with it's usual smoothness - subtle but noticable now it's back on song.
The signal from a dodgy MAP sensor will eventually cause the PCM to shut down the engine and cause a no start.

Moral: if you have a stumble and the '3 cycle of ignition key' trick throws a code 14 replace it (and the 90*rubber tubing underneath) asap otherwise you'll end up stranded :repair: