RAM Fault Code

Free · no signup

P229E

MIL (Check Engine Light) & Potential Derate.

System

Aftertreatment (NOx)

Symptom

MIL (Check Engine Light) & Potential Derate.

Diagnosis & fix steps

LOGIC: NOx Sensor 1/2 (Downstream) Circuit Malfunction. ACTION: Check the 4-pin connector at the sensor (located after the SCR catalyst). Verify 12V power, Ground, and J1939 CAN High/Low signals. If wiring is intact, replace the sensor

Red Seal field insights

Specs: J1939 resistance should be ~60 ohms. PRO-TIP: These are "smart" sensors with an integrated module. They won't start communicating on the CAN bus until they reach ~550°F (moisture-free).

Same code keeps coming back?

That's a program problem, not a part problem. Book a 30-minute uptime review with Grant, a Red Seal Heavy Duty Technician.

Book an uptime review

Read before you touch anything

  • This is general reference information, not a repair manual. It is for trained, qualified technicians.
  • Fault codes, meanings and procedures vary by model, serial number and software version. Confirm the code and the procedure against the manufacturer's service manual before acting.
  • Follow the OEM service manual, torque specs and your site's safety procedures: lockout/tagout, block raised equipment, relieve hydraulic, fuel and air pressure, and let hot systems cool.
  • You use this information at your own risk. Adventure Mechanical and AM Fleet Integrity accept no liability for damage, injury, downtime or loss arising from its use.
  • Not affiliated with or endorsed by any manufacturer. Brand names are used only to identify the equipment a code applies to.

Track this across your whole fleet

This code is free to read. AM Fleet Integrity lets your team log fault codes against assets, plus the full fault-code library, QR operator reporting, PM scheduling and predictive alerts. Start free — no credit card required.

Start your free trial

Related RAM fault codes

← All RAM fault codes