Buy 618-2176 - Genuine CAT DEF Module Manifold Left Side - wisentpartscenter.com

Description

Genuine Cat 618-2176 DEF manifold group, also called the DEF header or head unit. It mounts in the top of the DEF tank and is what pulls fluid out and feeds it to the SCR system, with the level, temp and quality sensing plus the filter all built into the one assembly. This is the short version at 272mm with a 4 pin DT connector, so measure your old unit and check the plug before ordering since the other numbers in this family are longer. Used on C series machines including D6T dozers, 953K track loaders, 930M small wheel loaders, 966M XE and 972M XE wheel loaders, 814K and 834K wheel dozers, 836K landfill compactors and 988K wheel loaders.

Purpose of the Part

This is the unit that draws DEF out of the tank and sends it to the SCR system in the right amount for the exhaust flow the engine is making, so the catalyst reacts the way it should. It covers a few jobs in one piece. The pickup pulls the fluid up from the tank, the level sensing tells the ECM how much is in there, the quality side reads the urea to water mix so the machine knows the fluid is still good, and the temp reading lets the system deal with cold weather. The ECM runs its dosing off all of that, so when one reading goes bad the machine pulls power even if there is nothing else wrong with it.

Issue Symptoms / When to Replace

Normally this shows up as a DEF or SCR light with a derate while the tank is full of good fluid. A bad level sensor or a stuck float gives you a gauge that reads wrong or sits in one place, so you get low DEF warnings that make no sense. A bad quality sensor calls good fluid contaminated and starts the derate countdown. On these headers the quality sensor is usually what goes first since ammonia works up into the top of the unit and eats the board. Before condemning it, look in the tank for debris or crystallized urea, check for bubbles sitting on the sensor and make sure the plug is clean and tight, all of that throws the same codes.

Signs to watch for are DEF and SCR fault lights, staged derate down to limp mode, a gauge that reads wrong or is frozen, low DEF quality messages, flat throttle response, less pull on grades and reduced top speed.

Related codes may include:

- P2033 DEF level sensor
- P207F DEF quality
- P20EE SCR NOx catalyst efficiency
- plus machine specific J1939 and CDL codes for DEF level, temp and quality

Brand Information

Caterpillar has been building heavy equipment for over 95 years with a parts catalog running past 1.4 million numbers. On a DEF header this matters more than on most parts since the ECM makes every dosing and derate call off what this unit reports. Cat builds it to their own emissions calibration and their own tank setup so the readings match what the machine expects. Aftermarket units can bolt in fine and still leave the machine derating because the sensors dont read the same.

Installation Notes

1. Take care of any engine, EGR, DPF or DOC faults first since SCR codes usually come from upstream.
2. Drop the DEF level below the manifold or drain the tank before pulling the old unit.
3. With the tank open check for sediment or crystal buildup and flush it out, dirty tanks are what kill these.
4. Check the filter and replace it if its loaded.
5. Order a gasket and mounting screws separately, they do not come with the manifold.
6. Set the new unit in with a fresh gasket, tighten evenly and dont overdo it.
7. Plug the connector in until it locks and make sure the pins are clean.
8. Clear the codes, let it cycle, then confirm level, temp and quality are all reporting right before it goes back to work.

How to Identify an OEM Part

Check the part number on the top of the unit where the connectors are and make sure it matches what you ordered. Also look at the header itself and make sure it looks like an OEM unit. A lot of aftermarket manufacturers change the way the header is built so the shape, the sensor box on top and the overall layout end up looking different from the original.

Why Buy 618-2176 from Wisent Parts

  • ⏱️
    Fast shipping
    Orders before 12PM EST ship same business day.
  • 🛡️
    180-day warranty
    All parts covered from delivery date.
  • ↩️
    Easy returns
    30-day returns.
  • ✅
    Verify fitment
    Send VIN/ESN and we’ll confirm.

Shop with confidence

Warranty & Return Information
Warranty Information

Wisent Parts offers a 180-day warranty on all parts from the date of delivery. This warranty covers orders placed directly through our website. If a part fails during this period, we’re here to help - whether it’s a replacement, repair, or refund. For full details, refer to the Warranty page.

Return Information

Wisent Parts accepts returns within 30 days of delivery. All returns are subject to a restocking fee. To qualify, parts must be unused and in their original condition. For full return instructions and restocking fee details, please refer to the Returns page.