P1618: How to Diagnose & Fix — Manufacturer-Specific Code (Chrysler/Dodge/RAM: Sensor Reference Voltage 1 Erratic)
2 vehicles · 1 makes · $200-$700 repair
How to diagnose and fix P1618: most-reported vehicles
Ranked by owner reports. Each card gives the symptoms, how to confirm the cause, the fix, parts and sources for that vehicle.
Volvo XC70 · 2001–2004
The ETM fails due to internal solder joint cracking, causing reduced power, limp mode, and check engine light. This is the same issue that affects all Volvo P2 platform vehicles (S60, V70, XC70). Volvo extended warranty coverage in some markets.
Common Symptoms
- Reduced engine power
- Limp mode
- Check engine light
- Rough idle
- Stalling
How to Fix
Replace the ETM with an updated revision that has improved solder joints. Clear adaptation values after installation. Some shops offer ETM rebuilds at lower cost than new units.
What you need to fix it
Only diagnosis- and fitment-reviewed repair parts are linked here.
- XeMODeX VO.1020.36001822.00.24-PP pre-programmed contactless ETM
replace a tested failed early ETM with a pre-programmed contactless dual-sensor remanufactured unit Fitment/availability: 2001 Volvo XC70 Turbo using a listed 36001821/36001822/8603652/8644344-family Magneti Marelli ETM; excludes 2002-20…
- XeMODeX VO.1020.30711554H.00.20 contactless electronic throttle body
replace the diagnosed later electronic throttle body after year, engine, original number and wiring checks Fitment/availability: 2002-2004 Volvo XC70 Turbo within the supplier's 2002-2007 application using listed 30711554/30711544/306500…
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Volvo S60 · 2001–2004
The 2001-2004 S60 (and other P2 platform Volvos) is notorious for ETM failure due to a design flaw in the throttle body electronics. The module develops internal solder joint cracks and corroded contacts, causing the car to enter limp mode, stall at idle, or refuse to accelerate. Volvo issued an extended warranty covering ETMs up to 10 years/200,000 miles, but many are now beyond that coverage.
Common Symptoms
- Check engine light with reduced engine power message
- Car enters limp mode (limited to ~30 mph)
- Stalling at idle or low speed
- Rough or surging idle
- Throttle unresponsive or delayed
How to Fix
Replace the ETM unit. Genuine Volvo replacement units have an updated design. Aftermarket options from Bosch are also available. Some specialists offer ETM rebuild services. Always reset the throttle adaptation values after replacement using a Volvo-compatible scanner (VIDA/DiCE).
What you need to fix it
Only diagnosis- and fitment-reviewed repair parts are linked here.
- XeMODeX VO.1020 pre-programmed contactless Volvo electronic throttle module
replace a scan-data-confirmed internal early ETM sensor failure with a VIN-preprogrammed contactless unit Fitment/availability: 2001 Volvo S60 Turbo and applicable 2001-2002 S60 non-turbo Magneti Marelli ETM branch; VIN and original-modu…
As an Amazon Associate, we earn from qualifying purchases; other part links may also earn au7o a commission. Confirm fitment by VIN before buying.
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P1618 code reference
General diagnostic-code context. The code alone does not confirm a cause for your vehicle; use the applicable issue card and its sources.
Frequently asked questions
What does P1618 mean?
P1618 stands for "Manufacturer-Specific Code (Chrysler/Dodge/RAM: Sensor Reference Voltage 1 Erratic)." P1618 is a manufacturer-specific powertrain code, most associated with Chrysler/Dodge/RAM. It generally indicates the PCM detected that the primary 5-volt sensor reference supply (Reference Voltage 1) is varying too much or too quickly. Many sensors share this reference, so an erratic supply can cause multiple sensor readings to fluctuate, leading to rough idle, stalling, or poor performance. The exact circuit should be confirmed against the specific vehicle's service data.
What are the most common causes of P1618?
The most common causes of P1618 are: Shorted or chafed sensor reference wiring, A failing sensor loading down the 5V reference circuit, Corroded or loose sensor connectors, Water intrusion in a connector on the reference circuit, Poor ground affecting the reference supply, PCM internal fault (less common). The specific cause varies by vehicle.
How much does it cost to fix P1618?
Repair costs for P1618 range from $200 to $700, depending on the vehicle and root cause.
Which vehicles are affected by P1618?
Au7o has documented P1618 across 2 vehicle models from 1 manufacturers: Volvo.
Content compiled with AI assistance using NHTSA complaints, TSBs, and owner reports. May contain errors. Always verify with your vehicle's service manual.